What ARPA actually covers

You were probably sent here by a page saying that the federal Archaeological Resources Protection Act does not govern the park you were asking about. This page says why, and what does govern it.

ARPA is real, it is strict, and it is the most misquoted statute in this subject. Three separate aggregator sites consulted during this project got it wrong in three different ways: one said it reaches "public, state, or federal lands", one said it is "the primary law that governs metal detecting" in a state, and one said it bars removing man-made objects over 100 years old "from public ground". None of those is what the statute says.

The one thing to take away

Stop asking whether ARPA applies and start asking who owns the ground.

ARPA reaches land the United States owns. It does not reach your state park, your county park or your city park, and no amount of the land being "public" changes that. If you are standing on municipal ground, the page that told you ARPA governs you has sent you to the wrong body of law entirely, and the rule that does govern you is your state's, which is what the rest of this directory is for.

And if you are on federal land, ARPA is still probably not the rule that decides your day. Two other federal rules do, and they point opposite ways: in a national park 36 CFR 2.1(a)(7) bans possessing the detector at all, and on national forest land 36 CFR 261.9 does not mention detectors and reaches what you dig or take. A third provision runs the other way: 36 CFR 228.4(a)(1)(ii) names metal detecting and exempts it from the notice-of-intent requirement on forest land, which is the only permissive mention of detecting in any instrument this project has read. All three sections are below. Which agency manages the parcel therefore matters more than ARPA does.

What the statute actually says

Read from the United States Code, 2024 edition, as published by the Government Publishing Office at govinfo.gov: 16 U.S.C. 470bb, 470cc and 470ee, each section retrieved and parsed in full on 4 October 2026.

The land it reaches, 16 U.S.C. 470bb(3)

"The term 'public lands' means - (A) lands which are owned and administered by the United States as part of -
(i) the national park system, (ii) the national wildlife refuge system, or (iii) the national forest system; and (B) all other lands the fee title to which is held by the United States, other than lands on the Outer Continental Shelf and lands which are under the jurisdiction of the Smithsonian Institution."

Plus "Indian lands", separately defined at 470bb(4) as tribal or individual Indian land held in trust by the United States or subject to a federal restriction against alienation.

That is the whole list. National parks, national wildlife refuges, national forests, other land in United States fee title, and Indian lands. A state forest is not a national forest. A city park is nowhere in that definition.

Note one thing that often gets read backwards: 470bb(6) defines "person" to include an officer or agent "of any State or political subdivision thereof". That is about who can be prosecuted, not about which land is covered. A state employee is a person under ARPA; a state park is not public land under ARPA.

The 100 years is real, and it is a floor rather than a test

This is where the 50-versus-100 confusion starts, so here is the mechanism in full. 470bb(1):

"The term 'archaeological resource' means any material remains of past human life or activities which are of archaeological interest, as determined under uniform regulations promulgated pursuant to this chapter. Such regulations containing such determination shall include, but not be limited to: pottery, basketry, bottles, weapons, weapon projectiles, tools, structures or portions of structures, pit houses, rock paintings, rock carvings, intaglios, graves, human skeletal materials, or any portion or piece of any of the foregoing items. Nonfossilized and fossilized paleontological specimens, or any portion or piece thereof, shall not be considered archaeological resources, under the regulations under this paragraph, unless found in archaeological context. No item shall be treated as an archaeological resource under regulations under this paragraph unless such item is at least 100 years of age."

So the statute does not simply declare everything over 100 years old to be protected. It says the regulations decide what is of archaeological interest, and that nothing under 100 years old may be treated as an archaeological resource at all. Age is a floor the regulations cannot go below, not a test that age alone satisfies. A 1974 beer can is not an archaeological resource. Neither is a 1920 one, in itself.

Where 50 years comes from, and why four states make it worse

Fifty years is National Register of Historic Places eligibility. It is a different scheme, under a different statute, for a different purpose: identifying what is worth listing. It has nothing to do with ARPA's threshold, and conflating the two is where the phantom "50-year ARPA rule" comes from.

What makes this harder is that some states genuinely do have 50-year rules, so a reader who has been told "50 years" is not always being told something false, just something that is not ARPA. Four real examples from this directory:

• Connecticut, Conn. Gen. Stat. 10-381(2): an "archaeological site" is a location with material evidence "not less than fifty years old" of past human life and culture in the state. 10-381(3) applies the same figure to an "archaeological artifact".
• Hawaii, HRS 6E-2: a "historic property" is one that is "over fifty years old" and meets the criteria for the Hawaii register. Two conditions, both required; age alone is not enough.
• Nebraska, Neb. Rev. Stat. 82-503(1): "No object shall be treated as an archaeological resource under this subdivision unless such object is determined to be at least fifty years of age." Note the structure, because it is ARPA's exactly, with a different number: archaeological interest and an age floor the definition cannot go below. Nebraska's floor is fifty, ARPA's is a hundred, and that is the whole difference.
• Arizona, A.R.S. 41-844(A): a reporting duty attaches to anything "at least fifty years old" discovered in the course of a survey or excavation on state, county or municipal land. Note separately that 41-841(B) defines an "archaeological specimen" as at least one hundred years old and expressly excludes arrowheads, coins and bottles, which covers most of what a detectorist actually finds. So when you see 50 years, the question is which state, not which federal statute.

What ARPA prohibits, 16 U.S.C. 470ee(a)

"No person may excavate, remove, damage, or otherwise alter or deface, or attempt to excavate, remove, damage, or otherwise alter or deface any archaeological resource located on public lands or Indian lands unless such activity is pursuant to a permit issued under section 470cc of this title, a permit referred to in section 470cc(h)(2) of this title, or the exemption contained in section 470cc(g)(1) of this title."

Note "or attempt to". The attempt is the offence too.

Penalties, 470ee(d): up to $10,000 and a year, rising to $20,000 and two years where the commercial or archaeological value plus the cost of restoration and repair exceeds $500, and up to $100,000 and five years for a second or subsequent conviction.

One carve-out, and read its wording closely. 470ee(g):

"Nothing in subsection (d) of this section shall be deemed applicable to any person with respect to the removal of arrowheads located on the surface of the ground."

It disapplies subsection (d), the penalties. It does not disapply subsection (a), the prohibition. So picking up a surface arrowhead on federal land is still within the prohibition; what the statute removes is the criminal penalty for it. That is a narrower carve-out than "surface arrowheads are fine", and the difference matters if anything other than a criminal fine is on the table: forfeiture, a citation, or being ejected.

The part nobody mentions: ARPA can reach a state-law violation

16 U.S.C. 470ee(c):

"No person may sell, purchase, exchange, transport, receive, or offer to sell, purchase, or exchange, in interstate or foreign commerce, any archaeological resource excavated, removed, sold, purchased, exchanged, transported, or received in violation of any provision, rule, regulation, ordinance, or permit in effect under State or local law."

Read that again, because it is the one place ARPA touches a reader who was never on federal land. If you take an archaeological resource in breach of a state rule or a city ordinance, and then sell it or carry it across a state line, that is a federal offence under ARPA, even though the digging itself was not. ARPA does not govern your city park. It governs what you do with what you took out of it, once that crosses a state border.

This is the practical reason the "which law applies" question is not academic. A state-law violation and a federal one can arise from the same find at different moments.

On federal land, the rule that stops you is not ARPA

In a national park, you do not get as far as ARPA. The National Park Service has its own regulation, and it is much broader.

Read from the Electronic Code of Federal Regulations at ecfr.gov, 36 CFR 2.1, retrieved and parsed 4 October 2026. Note that the eCFR states of itself: "It is not an official legal edition of the CFR." The official annual edition was not reachable at the govinfo paths tried on that date.

36 CFR 2.1(a), opening: "Except as otherwise provided in this chapter, the following is prohibited:"

36 CFR 2.1(a)(7):

"Possessing or using a mineral or metal detector, magnetometer, side scan sonar, other metal detecting device, or subbottom profiler."

Possessing. Not using, not digging, not finding. Carrying it. In a national park the offence is complete when the machine is in your hand, switched off, having found nothing. No archaeological resource need exist anywhere nearby.

There are three stated exceptions, and the first is the one that matters to a visitor:

"This paragraph does not apply to:
(i) A device broken down and stored or packed to prevent its use while in park areas. (ii) Electronic equipment used primarily for the navigation and safe operation of boats and aircraft. (iii) Mineral or metal detectors, magnetometers, or subbottom profilers used for authorized scientific, mining, or administrative activities."

So what you do differently: if your route to a legal site crosses national park land, break the detector down and pack it so it cannot be used. Packed, you are inside exception (i). Assembled on the back seat, you are not, because the prohibition is on possession.

And a national forest is not a national park

Added 5 October 2026. This was the gap, and it was found the way the Washington state parks rule was found: three of the generated city articles cited a provision no page of ours did.

Read from the Electronic Code of Federal Regulations at ecfr.gov, 36 CFR 261.1 and 261.9, retrieved and parsed 5 October 2026. The eCFR states of itself that "It is not an official legal edition of the CFR."

The Forest Service has its own prohibitions, and they are nothing like the Park Service's.

Where they apply, 36 CFR 261.1(a)(1): the prohibitions apply when "an act or omission occurs in the National Forest System or on a National Forest System road or trail."

36 CFR 261.9, "Property", the provisions that bear on detecting:

"The following are prohibited:
(b) Removing any natural feature or other property of the United States.
(g) Digging in, excavating, disturbing, injuring, destroying, or in any way damaging any prehistoric, historic, or archaeological resource, structure, site, artifact, or property.
(h) Removing any prehistoric, historic, or archaeological resource, structure, site, artifact, property."

The words "metal detector" do not appear in it. So on National Forest System land, the detector itself is not what is regulated. What is regulated is digging into or removing a prehistoric, historic or archaeological resource, and separately removing "any natural feature or other property of the United States".

That is the opposite structure to a national park, where 36 CFR 2.1(a)(7) bans possessing the machine at all. The two federal agencies that manage most of the land a detectorist might drive to answer the question differently, and the boundary between them is not marked on the ground in any way you can see.

So what you do differently: work out which federal agency manages the parcel before you decide anything, because the answer flips completely.

The one federal provision that names metal detecting and permits it

Everything above tells you what federal law prohibits, and a reader who stops there draws the wrong conclusion: that federal land is uniformly closed. It is not, and for national forests there is a provision that says so in terms.

36 CFR part 228 subpart A governs mining operations on National Forest System land. 228.4(a) requires a notice of intent to operate from anyone proposing operations "which might cause significant disturbance of surface resources" – and then:

36 CFR 228.4(a)(1): "A notice of intent to operate is not required for: … (ii) Prospecting and sampling which will not cause significant surface resource disturbance and will not involve removal of more than a reasonable amount of mineral deposit for analysis and study which generally might include searching for and occasionally removing small mineral samples or specimens, gold panning, metal detecting, non-motorized hand sluicing, using battery operated dry washers, and collecting of mineral specimens using hand tools."

Read from the eCFR, title 36, part 228 subpart A, section 228.4, 8 October 2026.

This is the only provision found anywhere in this project – federal or state – that names metal detecting and names it permissively. Every other instrument on this page and in the directory either prohibits it, conditions it on permission, or does not mention it.

Now the limit, because it is narrower than it first reads. The provision says a notice of intent is not required. That is not the same sentence as "detecting is allowed", and three things still apply:

• Part 228 is mining regulation. The exemption tells you that swinging a coil is not an "operation" needing a filing with the District Ranger. It is not a grant of permission to detect, and it was never the detecting permit scheme that secondary guides take it for.
• 261.9 still reaches the recovery. Digging into or removing a prehistoric, historic or archaeological resource is prohibited whatever 228.4 says about paperwork, and 261.9(b) separately reaches removing "any natural feature or other property of the United States".
• The forest's own orders still apply where posted. See below. So the honest reading is: on national forest land you do not need to file anything to look, you may still not dig into a resource, and a posted order may close the ground you are standing on. Two cautions on reading any of this as blanket permission. First, 261.9(b) prohibits "removing any natural feature or other property of the United States", which is broad on its face and we have not established how it is applied to an ordinary modern find. Do not read the right-hand column as saying a national forest is open. Second, individual forests close and restrict areas by order, and the mechanism is worth knowing because it is checkable. 36 CFR 261.50(a) empowers the Chief, Regional Foresters and unit heads to "issue orders … that close or restrict the use of described areas by applying the prohibitions authorized in this subpart". 261.50(c) requires each order to describe its area, state each prohibition applied, and be posted; 261.51 defines posting as filing a copy at the Forest Supervisor's and District Ranger's offices and displaying each prohibition "in such locations and manner as to reasonably bring the prohibition to the attention of the public". The penalty for breaching an order is 261.1b: not more than six months, a fine under 18 U.S.C. 3571, or both. So what you do differently on national forest land: do not look for a permit, because 228.4(a)(1)(ii) says you need no filing. Ask the district office which orders are in force for the ground you want, because an order is a document that must be posted and can be shown to you. Those two questions together are the whole answer, and they are different questions from the one most guides tell you to ask. Read from the eCFR, 36 CFR 261.50, 261.51 and 261.1b, 8 October 2026. And ARPA sits behind both of them. A national forest is inside ARPA's definition of public lands at 470bb(3), so everything above about the 100-year floor and the 470ee penalties applies there too. 261.9 is an additional layer, not a replacement.

How this was found, because the method matters more than the provision

Not by a sweep and not by a search. citation_gap.py was built to audit the generated city articles against this directory, and it reported that the Washington, Oregon and Idaho articles all cited 36 CFR 261.9 while no page of ours did. One of those three applied it wrongly, to Oregon state parks and the state-owned ocean shore, and that was corrected. The other two applied it to federal land, correctly in direction. So the generator was right that the provision existed and right about roughly where it bites, and this directory simply did not have it.

That is the second time in two days a check pointed at someone else's work has found a gap in ours, the first being Washington's WAC 352-32-235. It is worth expecting rather than being surprised by.

The other statute you will be told governs you, and it does not

Added 6 October 2026. After ARPA, the federal law most often quoted at detectorists is the National Historic Preservation Act, usually as something like "NHPA protects sites listed on the National Register of Historic Places." Two posts in our own network said exactly that.

Read from the United States Code, 2024 edition, as published by the Government Publishing Office at govinfo.gov: 54 U.S.C. 306108, retrieved 6 October 2026. This is section 106, the provision people mean. Here it is in full, because its shape is the whole point:

"The head of any Federal agency having direct or indirect jurisdiction over a proposed Federal or federally assisted undertaking in any State and the head of any Federal department or independent agency having authority to license any undertaking, prior to the approval of the expenditure of any Federal funds on the undertaking or prior to the issuance of any license, shall take into account the effect of the undertaking on any historic property. The head of the Federal agency shall afford the Council a reasonable opportunity to comment with regard to the undertaking."

Read who it is addressed to. "The head of any Federal agency." It is a procedural duty on government, owed before government spends federal money or issues a licence, and the duty is to take into account and to let the Advisory Council comment.

It prohibits nothing. It says nothing at all to a member of the public.

So if you are told that a park is on the National Register and that NHPA therefore stops you detecting there, the statute being cited does not do that job. Whether you may detect still turns on who owns or manages the ground and what that owner's own rules say.

Why this keeps happening: a designation is not a jurisdiction

It is the same confusion that produces most of the bad advice in this subject, and it has three forms worth being able to spot.

• A listing read as a prohibition. National Register or National Historic Landmark status is a designation under the NHPA. It does not restrict what a landowner or a visitor may do, and it does not transfer ownership. One post told readers that two St. Louis city parks were "federal landmarks" carrying felony exposure. They are city parks with a listing.
• A listing read as permission. The inverse, and just as costly. Cumberland Island was recommended to readers as a detecting destination; it is a National Seashore, so NPS land, where 36 CFR 2.1(a)(7) prohibits possessing a detector at all.
• A designation that may not have happened yet. Texas's Antiquities Code says qualifying sites on public land "are state archeological landmarks and are eligible for designation". Whether a given site is already a landmark or merely eligible to become one is not answered by that sentence. What to do differently: when you meet a claim that somewhere is federal, protected or landmarked, ask two questions in this order. Who owns or manages the parcel? Then: what actually follows, for me, from the designation itself? The second answer is very often nothing at all.

The exception that proves the rule: Washington, DC

Every other page in this directory exists partly to explain that ARPA does not reach the ground you are standing on. The District of Columbia is where that inverts.

Much of the District's parkland is National Park Service land. The DC Department of Parks and Recreation publishes no metal detecting rule at all. So in Washington the federal regime is not a distraction from the real rule, it very often is the real rule, which means 36 CFR 2.1(a)(7) and its possession offence rather than ARPA's excavation offence.

The practical question in DC is therefore not "what is the rule" but "whose land is this park", and the answer changes from park to park. See the District of Columbia page.

Not established, and we say so rather than estimating: the parcel-level split of DC parkland between the Park Service and DPR. That would need both agencies' land inventories, and this project has not done it. Check the specific park.

Summary

A shared explainer. It is linked from every state page that invokes it and is never restated inline, so one correction here fixes every page that depends on it.

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