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 stops you. See the National Park Service section below. That rule is stricter than ARPA and it catches you earlier.
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 three 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. Three 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.
- 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.
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
| ARPA, 16 U.S.C. 470aa to 470mm | NPS rule, 36 CFR 2.1(a)(7) | |
|---|---|---|
| Land | National parks, refuges, forests; other US fee land; Indian lands | National Park System units |
| Offence | Excavating, removing, damaging, defacing, or attempting to | Possessing or using the device |
| Needs a find? | Yes, an archaeological resource at least 100 years old | No |
| Your state park | Not covered | Not covered |
| Your city park | Not covered, except 470ee(c) on interstate sale | Not covered |