Where every figure on this site comes from

What it is. The Bureau of Land Management publishes its Areas of Critical Environmental Concern as a public map service, BLM_Natl_ACEC. One layer, "ACEC Designated Polygons," is the list of areas BLM designates today. A second layer holds areas that used to be designated or were replaced. Every area on this site comes from the first. We don't count the second. This site shows designated areas only. Nominations under consideration in open plans aren't on it.

When we read it. Our system reads both layers and saves every read. The read behind this site finished Oct 20, 2026, 8:25am PT. It found 1,120 areas, covering 25,007,674 acres, across 11 BLM state offices. Each area carries the date we first read its values and the date of the latest read that found it unchanged.

BLM's own published count. BLM's yearly Public Land Statistics prints a national table, Table 5-15, of 1,171 "areas of critical environmental concern and research natural areas", covering 21,530,625 acres, counted on September 30, 2024. It's a different count from this map's on three counts: it adds research natural areas to the ACECs, it's dated before 50 New Mexico areas left BLM's map (it gives New Mexico 161, and the map has 112 today), and its acres come from BLM's surface management database, not from the lines. This site counts the areas on BLM's map, and says which day.

How we read it. We copy BLM's fields as BLM writes them: the name, the land use plan that designated the area, the NEPA number, the Record of Decision date, the acreage, and BLM's yes-or-no answer for each of its eight relevance findings, four importance findings and two special management fields ("protect" and "prevent"). The labels on those findings are BLM's own field labels, read from the service. The acreage is BLM's, computed by BLM from its own lines. We repair a shape only when BLM's is geometrically broken, keep BLM's verdict on it, and never change an acreage.

When an area changes. If an area's values change or BLM's map stops showing it, we record the change as its own dated event and save the old values. By August 24, 2026, 50 areas in New Mexico (212,272 acres) were off the map. BLM's map stopped showing them on Aug 24, 2026. BLM's list of past areas doesn't carry them either, and we found no plan decision removing them. They're still in our records, with the date we saw them go and what the last read held. Nothing else has changed in BLM's list since we started reading it on August 14, 2026.

Our older count. Before August 2026 our records held 1,001 ACECs, taken from the national Protected Areas Database (PAD-US). When we switched to BLM's own service we reconciled the two lists area by area, by shape rather than by name, and wrote the result up in our records, a second time against today's list. Every difference is accounted for there, and what we can't explain is counted as unexplained.

Two areas of nearly one name. BLM's map carries the South Pass Historic Landscape ACEC and the South Pass Historical Landscape ACEC: 53,773 acres in the Rock Springs Resource Management Plan (December 22, 2024) and 158,545 acres in the Lander Resource Management Plan (June 26, 2014). They're two areas from two plans, not an old and a new version of one. Both are on BLM's layer of designated areas, and their lines meet along about 19.5 km, overlapping on 10.4 acres. We count both, as BLM's map does. BLM's list of past areas carries the earlier ones: the Lander Resource Management Plan's South Pass Historic Mining Area ACEC (14,106 acres, 1987) and the Green River Resource Management Plan's South Pass Historic Landscape ACEC (63,474 acres, 1997). It also carries a row for the South Pass Historical Landscape ACEC with the same acres and date as the designated one.

What it is. Our records hold the public authorizations for extraction and development on federal land: mining claims, oil and gas leases, geothermal leases, rights of way for roads, pipelines and power lines, and grazing allotments, each from the agency system that issues it.

How we measured it. For each ACEC we counted the authorizations whose mapped point falls inside BLM's own boundary for that area, tested against the real shape. The point comes from the land description BLM records, not from the ground: BLM's records place a mining claim only by the quarter section or other survey unit it sits in, so a claim near the edge of a line can count on either side of it. A grazing allotment is a mapped area, so the one point we hold for it says little. We also counted the allotments whose mapped footprint touches an area, 3,238 in all, and the ones that lie wholly inside, 124. A zero means we measured and found nothing placed inside.

Status. Each one counts by the word BLM's case record gives it. A mining claim BLM lists as Active, or a lease or right of way it lists as Authorized, counts as active. A claim BLM lists as Filed, Under Review or Submitted counts apart, as filed and pending: BLM defines Filed as "A claim for which data entry is completed, and the claim is then waiting on the final land status review." (BLM's MLRS presentation). A lease BLM lists as Closed or Interim isn't counted: 60 geothermal leases BLM lists as Closed and 14 oil and gas leases BLM lists as Interim. An area page names those apart.

Grazing, by footprint. A grazing allotment is a land unit, often tens of thousands of acres, and our records place it at one point. By that point, allotments sit inside 265 areas. By the allotment's own boundary, read Oct 20, 2026, 9:30am PT, 2,778 allotments touch 789 areas, so that's how we count them: an allotment whose boundary touches a line counts once for that line. An area has nothing inside only when no claim, lease or right of way has its point inside the line and no allotment touches it. BLM's allotment map doesn't cover Alaska: it holds 21,208 allotments and none there, so for its 40 areas we count claims, leases and rights of way only.

When. The count behind this site was made Oct 20, 2026, 8:30am PT, against the 1,120 areas on BLM's map. 945 of them have something placed inside: at least 11,740 active mining claims and leases, at least 6,353 more claims filed and pending, 4,646 rights of way, and a grazing allotment on part of 789. The other 175 have nothing placed inside. Each authorization counts once for each line it sits in, and 15 sit in two lines that overlap. The 50 areas BLM's map stopped showing aren't counted, and their pages show no count.

When a claim was located. Whether a claim was located before its area was designated is one of the first things a reader of a claim asks. BLM's public Serial Register Page prints each claim's date of location, one report at a time, about three seconds a claim (100 claims took 325 seconds on October 18, 2026). BLM's case search answered with an error the same day. So we read it in slices, the areas with the fewest claims first: by Oct 18, 2026, 11:59am PT, 400 of the 17,526 claims inside the lines (a claim in two lines counted once), every claim in 35 of the 205 areas that hold one. An area page says how many of its claims were located before the designation only when every one of its claims is read. A lease's effective date is in the records we hold, and an area page with leases says how many took effect before the area was designated.

What the acreage means. Where we show acres for authorizations, it's the acreage each authorization records for itself, added up. One that's partly inside an area counts with its whole recorded acreage. That's a measure of what's been authorized, not of ground disturbed.

Where the claims come from. BLM's Mineral & Land Records System keeps a serial index of every mining claim (its public report 106, the Serial Number Index). The Nevada Division of Minerals publishes a copy of it for 10 western states (Oregon and Washington as one), and its copies, edited Oct 20, 2026 and read by us the same day, list 563,300 open claims. Our records hold 563,296 of them. Until Oct 18, 2026 they held only the claims BLM's claims map draws (the layer BLM calls "Case", read until it has no more rows to give): that's 192,391 of the index, about a third.

• Nevada: 272,669 in the index: 84,522 on BLM's map, 149,526 placed by land description, 38,621 unplaced.
• Arizona: 65,783 in the index: 21,190 on BLM's map, 39,397 placed by land description, 5,196 unplaced.
• Wyoming: 43,960 in the index: 12,853 on BLM's map, 30,268 placed by land description, 839 unplaced.
• Utah: 42,060 in the index: 19,702 on BLM's map, 19,807 placed by land description, 2,551 unplaced.
• Idaho: 41,394 in the index: 17,449 on BLM's map, 18,922 placed by land description, 5,023 unplaced.
• Montana: 28,914 in the index: 6,943 on BLM's map, 20,119 placed by land description, 1,852 unplaced.
• California: 27,403 in the index: 9,354 on BLM's map, 15,391 placed by land description, 2,654 unplaced.
• New Mexico: 14,571 in the index: 5,740 on BLM's map, 8,632 placed by land description, 199 unplaced.
• Colorado: 13,823 in the index: 8,041 on BLM's map, 4,917 placed by land description, 865 unplaced.
• Oregon and Washington: 12,723 in the index: 6,597 on BLM's map, 5,824 placed by land description, 302 unplaced.

How we placed them. A claim BLM's map draws keeps BLM's place for it. Every other claim we placed at the middle of the smallest piece of the Public Land Survey its land description names, on BLM's survey layer (CadNSDI): 203,485 at a section, 101,664 at a quarter section, 7,202 at a quarter-quarter section and 489 at a survey lot. A section is about 1.6 km across, so a claim placed at a section can sit anywhere in that square, not just at its middle. Most sit at a section because outside Nevada, Montana, New Mexico and Oregon, BLM's survey layer carries no labels on a section's quarters, so a quarter the record names can't be found there. We didn't split a section to make one.

A check on the placement. For 300 placed California claims, our point sits a median 569 m from the middle of the copy's own points for the same claim, about the distance from a section's middle to a quarter's. 5 of them lie farther off than one and a half times the half-width of the piece they were placed in.

What couldn't be placed. 58,102 claims name no piece of surveyed land we could find, so they have no point and sit inside no line:

• 53,638, where the section is unsurveyed (BLM's survey layer holds the township's unsurveyed part and no section).
• 1,903, where the parts its land description names lie more than 4 km apart, so no one point stands for the claim.
• 1,530, where the township is in BLM's survey layer and the section isn't.
• 850, where the township isn't in BLM's survey layer.
• 181, where the land description doesn't parse.

37,573 of the 53,638 in unsurveyed sections are in Nevada. They count in each state's figures above and in no area's. So every claims count on this site is a floor and says "at least".

Claims the index doesn't list. BLM's claims map carried 10,429 claims in our last read of it that the index, as edited Oct 20, 2026, doesn't list. We haven't checked why. They stay in our counts until the next read of the map. And 45 claims our records took from an earlier read of the copies aren't in them now (10 in Colorado, 9 in Idaho, 6 in Nevada and 20 in Oregon and Washington). The index lists open claims, so most likely they've closed, but BLM's case record would have to say so. We keep them and don't count them in the index's 563,300. The other way, 4 of the index's claims aren't in our records yet.

What the old gap looked like. BLM's map drew few of the claims converted from its older records system, LR2000. In California the index lists 16,081 claims with serials from CA1013 to CA1020. BLM's map drew 674 of them, and our records hold 16,081 now.

Two placements, five areas. For five areas the fact check named, we tested the copy's own points against BLM's lines beside ours. A claim near a line can land on either side of it by either placement.

• Fremont-Kramer: 2,179 by the index's placement, 2,171 by ours.
• Pinto Mountains: 1,315 by the index's placement, 1,203 by ours.
• Green Mountain: 681 by the index's placement, 651 by ours.
• Ivanpah: 1,487 by the index's placement, 1,340 by ours.
• Superior-Cronese: 788 by the index's placement, 673 by ours.

Who holds them. The index names each claim's claimants. Where it names one, that's the holder. Where it names several, the claim is listed under several claimants and we don't pick one. The names stay in our records. A claimant the index masks is withheld by BLM, as on BLM's own Serial Register Page.

Why the map alone can't say. BLM's map of mining claims and leases shows where each one is and what kind it is, but it has no field for who holds it. BLM records the holder in a different system, the Mineral & Land Records System (MLRS), on each case's own public page at mlrs.blm.gov, one case at a time. So for every authorization inside an ACEC we read that page and take the holder exactly as BLM lists it: the claimant on a mining claim, the lessee on a lease, the holder of a right of way, each with the page we read it from and the date. A claim our records hold from BLM's serial index takes its claimants from the index, as above.

By Oct 20, 2026, 8:18am PT, that gave a holder's name for 15,471 of the 17,531 mining claims inside ACECs, 434 of the 565 oil and gas leases, 43 of the 71 geothermal leases and 4,365 of the 4,646 rights of way.

Withheld by BLM. BLM doesn't show private individuals' names on its public pages. Its public Serial Register Page prints such a holder as "XXXXXXXXXX," under the Privacy Act, and still says what role they hold. Where a claim's case page lists nobody, we read that register page, and where it shows a hidden name we say the claimant is withheld by BLM under the Privacy Act. 1,832 authorizations inside ACECs read that way.

Withheld by this site. BLM's case pages and its serial index also name private individuals, and some companies' lines name a person after "ATTN". We don't print a private person's name. Every holder goes through one test before a page can show it: a name that isn't a business, a tribe or an agency (no word like LLC, Inc., Company, Mining, Resources, Trust, County, District, Department or Field Office, and no agency's own abbreviation) is shown as "A private individual, name withheld by this site", and so is a living, revocable or family trust named for a person, an estate, an "et al." or an "Esq." An "ATTN" or "c/o" line, or a person's name in parentheses after a company's, is cut off, and a case name that repeats a masked or cut-off person's name isn't shown. A hand list, read by eye against every holder name in the record, settles the edge cases both ways. A name the test doesn't know is masked, never shown. On the read of Oct 20, 2026, 8:18am PT that masked 103 authorizations held by 94 people, and cut an "ATTN", "c/o" or parenthesis line from 283 more. The rule is scripts/lib/privacy.mjs, and the build refuses a file it would mask differently.

What it is. RIN 1004-AF53, "Planning and Designation of Areas of Critical Environmental Concern," a Department of the Interior rule. We read the government's own record of it from reginfo.gov, the site of the White House Office of Information and Regulatory Affairs (OIRA): the Unified Agenda entry and the review record, last read Oct 20, 2026, 9:29am PT.

What it says so far. BLM's abstract and the government's "EO 14192 Designation: Deregulatory" label are quoted on this site word for word, from reginfo.gov. OIRA received the rule for review on July 13, 2026 and concluded its review on October 8, 2026, "Consistent with Change," after 87 days.

Who met with OIRA. We list every meeting OIRA records for this rule, seven meetings, plus one group OIRA lists as a no-show, with the date, who asked for the meeting, who sat in it, its status as OIRA records it, and a link to OIRA's own meeting page. We save a copy of each meeting page as we read it. The rule and its meetings.

The text. It's a proposed rule, and its text isn't public until it's published in the Federal Register. We check the Federal Register, both its published documents and its public inspection desk, where documents appear a day or more before they publish. We check the Federal Register and its public inspection desk every 15 minutes. It wasn't there at our last check, Oct 18, 2026, 12:36pm PT. When it appears, its dates and the comment deadline come from the Federal Register and regulations.gov.

Every legal quote on this site is copied from its official source with the address and the time we read it, and it's checked word for word against the live source before the site is built.

• FLPMA, 43 U.S.C. 1702(a) (the definition of an ACEC) and 43 U.S.C. 1712(c)(3) (land use plans must "give priority to the designation and protection of areas of critical environmental concern"): the United States Code, 2024 edition, from the Government Publishing Office, read Oct 18, 2026.
• 43 CFR 1610.7-2 (how BLM identifies and designates ACECs): the electronic Code of Federal Regulations, its text of October 8, 2026, read Oct 18, 2026. That's the text in force today. BLM's 2024 Public Lands Rule, "Conservation and Landscape Health" (89 FR 40308), had rewritten it. A final rule published May 12, 2026, "Rescission of Conservation and Landscape Health Rule" (91 FR 25787), rescinded the 2024 rule and put this text back, effective June 11, 2026.
• BLM Manual 1613 (BLM's guidance on relevance and importance, 1988): BLM publishes it only as a scanned image with no text in it. We typed the passages we quote from the page image, checked them against an automated reading of the same page (100.0 percent, 99.1 percent, 98.2 percent of words agree), and recorded a checksum of BLM's file, so a changed scan shows. The manual quoted here is BLM's 1988 release. BLM replaced it on August 7, 2024, and rescinded that replacement on May 29, 2026 with none in its place: "Both regulatory and policy procedures for ACECs are under review for revision." We found no BLM statement that the 1988 text governs again. We quote it for how BLM long read the rule's two tests.
• The rule's abstract and the EO 14192 label: reginfo.gov, as above, read Oct 18, 2026.
• The 2024 Public Lands Rule and its rescission: the 2024 rule (89 FR 40308, FR Doc. 2024-08821, effective June 10, 2024) rewrote 43 CFR 1610.7-2. BLM proposed rescinding it on September 11, 2025 (90 FR 43990, FR Doc. 2025-17537), and the final rescission (91 FR 25787, FR Doc. 2026-09386, effective June 11, 2026) put the section back as it stood before. The preamble's words on ACECs that we quote are cut from the Federal Register's full text, read Oct 18, 2026.
• The two plan notices and BLM's manual transmittals: the Rock Springs and western Oregon notices from the Federal Register, and BLM's transmittal sheets for its 2024 manual and its rescission, from BLM's own files, text and date read from each, Oct 18, 2026.
• The dates in the history on The rule are read from each document: the Federal Register's own record for its documents, BLM's transmittal sheets for the manuals, the U.S. Code's source note for FLPMA and eCFR's for the 1983 rule.

The boundaries are BLM's own shapes from the same read, simplified so the map loads quickly: about 560 meters of tolerance for the national view, about 56 meters for a state, and about 5.6 meters on an area's own page. At the area level every simplified shape's area is within 2.2 percent of the area of BLM's own shape. The ground under the maps is the U.S. Geological Survey's National Map.

Where one of BLM's areas is the same ground as an ACEC in our records system, we link to that record. "Same ground" means the two shapes overlap by at least half of the smaller one. 946 of the 1,120 areas on BLM's map match one of our records this way and 174 don't. Those record pages ask you to sign in, so for now an area's page doesn't link to its record.

The front door's foot is one line and a door to here. These are its sourcing lines, as they stood at the foot of that page until October 20, 2026 (lane cl-under-map-build-1020), word for word, every figure from data/.

• The areas, the acres, the states and what BLM found: the Bureau of Land Management's own map of designated ACECs, read Oct 20, 2026, 8:25am PT. The 1,120 are the areas on it that day. BLM's map stopped showing 50 areas in New Mexico in August 2026, and they aren't counted. Acres are BLM's own, measured from its lines.
• What's inside: our count, made Oct 20, 2026, 8:30am PT: the mining claims, leases and rights of way in our copy of BLM's land records and leasing systems, each placed at one point from BLM's land description and tested against BLM's real line for the area, and every grazing allotment whose boundary touches the line, read Oct 20, 2026, 9:30am PT. Active is BLM's own word on the case (Active for a claim, Authorized for a lease or a right of way). A claim BLM lists as Filed, Under Review or Submitted is counted apart as filed and pending, and a lease it lists as Closed or Interim isn't counted. All 1,120 areas were checked. Claim counts are a floor: of the 563,300 open claims in BLM's serial index (the Nevada Division of Minerals' copies of BLM report 106, edited Oct 20, 2026 and read by us the same day), 58,102 couldn't be placed on the ground, so they sit inside no line. Read how we placed them.
• The law and BLM's guidance: 43 U.S.C. 1702 and 1712 from the 2024 Code on govinfo.gov. 43 CFR 1610.7-2 from eCFR, its text of Oct 8, 2026. BLM Manual 1613 (1988), copied from BLM's scan, page 7: BLM's 1988 manual, replaced in 2024. BLM rescinded the 2024 manual on May 29, 2026 and hasn't issued another. Each quote was copied Oct 18, 2026, with its address.
• The proposed rule: RIN 1004-AF53, "Planning and Designation of Areas of Critical Environmental Concern," from its Unified Agenda entry on reginfo.gov, read Oct 20, 2026, 9:29am PT. The abstract and the "Deregulatory" label are the government's words. The meetings, seven meetings, plus one group OIRA lists as a no-show, are from OIRA's own meeting pages. Not in the Federal Register or on its public inspection desk at our last check, Oct 18, 2026, 12:36pm PT.
• Nearest to you: the middle of your ZIP, from the Census Bureau's 2020 ZIP Code Tabulation Area Gazetteer (census.gov, published January 22, 2021). Each distance runs from there to the nearest edge of a line, in miles.
• This page was built Oct 22, 2026, 5:45pm PT.

• BLM's list doesn't name a field office. The service gives the land use plan that designated each area but no field office, so we don't show one.
• 471 areas have no NEPA number in BLM's list (BLM leaves the field blank), and 3 have no real Record of Decision date (BLM's placeholder 9999-09-09). We show those as missing, not as dates.
• 50 areas BLM's map stopped showing in August 2026. BLM's list of past areas doesn't carry them either, and we found no plan decision removing them. We don't count them, and we don't know why the map dropped them.
• 174 areas have no matching record page in our system yet. 15 of them touch one of our records without being the same ground, and 159 overlap none.
• Mining claims are a floor. 58,102 of the 563,300 open claims in BLM's serial index couldn't be placed on the ground, most in unsurveyed sections, so they sit inside no line. Most of the claims we placed sit at a section's middle, not at the claim. The index copy we read has no Alaska or South Dakota, so there we hold only the claims BLM's map draws. Read how we hold BLM's claims.
• The authorization counts are only as complete as the agency systems we read. An authorization with no recorded location can't be placed inside or outside an area and isn't counted. Footprints exist mostly for grazing, so the footprint counts describe grazing far better than mining or energy.
• Holders. 228 mining claims inside ACECs show no holder at all on BLM's pages, and BLM's pages list no holder for 131 oil and gas leases, 28 geothermal leases and 281 rights of way inside them. We show those as not listed by BLM. We don't yet check the register page for a person withheld beside a named company on the same claim. Grazing permits come from a different BLM system that we don't read for holders yet, so none of the 2,778 grazing allotments touching ACECs shows a permittee.
• Our older count of 1,001 came from an older national list. The reconciliation names what in it we can't explain.
• The proposed rule's text isn't public yet. Until it is, we quote only BLM's abstract, the government's own label and the dated record around it, and we don't say what the rule will do.
• BLM Manual 1613 exists only as a scan, so our quotes from it are a transcription, checked by eye and by machine.

No corrections yet. This list started October 18, 2026. Every correction we make to a fact on this site goes here, with the date, the page and what changed.

If something on this site is wrong, tell us at ask@morethanjustparks.com so we can correct it.

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