How to Research Spots to Metal Detect

Most detectorists never get past the same three city parks because they don't know where else to look. The detectorists pulling silver and old relics every weekend aren't using better machines — they're using better information. This guide walks through how to find spots no one else hunts: historical topographic maps, Sanborn fire insurance maps, old aerial photos, LIDAR, local archives, and the field signs that tell you something used to be there. Most of what you need is free and online. If you're brand new to detecting, start with the complete beginner's guide first; this article assumes you can swing and want to know where to swing next.

1. Why research is the highest-leverage skill

Two detectorists with identical machines, swinging side by side, will have wildly different days. The variable that matters most isn't the detector or the technique — it's the ground underneath them. A mediocre swing in 1880s ground beats a perfect swing in 1990s ground every time. There are no silver coins where silver coins were never lost.

The math is simple: most US public parks were laid out after 1950. The coins lost there are post-1950. The detectorists who consistently pull pre-1900 silver — Indian Head cents, Barber dimes, Seated Liberty coins (we cover all of these in how to identify old coins) — are detecting on ground that was active in pre-1900: old crossroads, abandoned schoolhouse sites, vanished homesteads, fairgrounds that became cornfields, picnic groves that became suburbs. None of those show up in modern Google Maps. All of them show up if you know where to look.

The good news: the research is free, the maps are public, and most hobbyists never bother. An hour with old maps before a hunt typically pays back better than a $500 detector upgrade.

2. Historical USGS topographic maps

The single most useful research tool for North American detecting is the historical USGS topographic map. The US Geological Survey has mapped most of the country since the 1880s and updates the maps every 10–30 years per quadrangle. Old topos show buildings, schools, churches, mills, cemeteries, named places, roads, and railroads that have since vanished — exactly the categories that produce coins and relics.

The free portal is USGS topoView. Drop a pin on the area you want to investigate, then scrub through the available years on the right-hand timeline. The trick is to find a spot where an older map shows something — a black square representing a building, a small italic name, a school symbol — that the modern map no longer shows. That's a candidate site.

What to look for on old topos:

• Black squares — individual buildings. A square in the middle of what is now an open field is gold.
• "Sch." — one-room schoolhouses, very productive because every child shed coins at recess.
• "P.O." — old post offices, often inside general stores.
• Named hamlets — small settlement names that have since disappeared. The labels themselves often mark the center of the lost community.
• Mill symbols and dotted millraces — old industrial sites with worker traffic.
• Cemeteries — never detect inside them, but they often mark the location of vanished churches and the surrounding picnic and event areas.
• Crossroads in the middle of nowhere — old taverns, blacksmith shops, wagon stops.

3. Sanborn fire insurance maps

For any town that existed between roughly 1867 and the 1970s, the Library of Congress Sanborn collection is the most detailed historical resource you'll ever use. Sanborn maps were produced for fire insurance underwriters and show every building in town, color-coded by construction material, with footprints, street addresses, and use (saloon, hotel, livery, dwelling).

Sanborns let you do something topographic maps can't: find the exact footprint of a vanished hotel that stood at the corner of Main and Elm in 1894. If you can place a Sanborn map over a modern aerial, you'll often find that the corner is now an empty lot, a parking area, or a small park — directly accessible.

Coverage is town-by-town. Every state has Sanborn maps for at least its larger towns; smaller settlements may or may not be covered. The LoC site is searchable by state, then town. Many state libraries and university archives also host Sanborn collections with later editions.

4. Aerial photography, then and now

Modern satellite imagery shows the ground today. What you really want for detecting is the ground 50 years ago — before half the foundations were bulldozed, before the woods reclaimed the cleared fields. Two tools handle this:

HistoricAerials

HistoricAerials.com is the easiest interface for older US aerial photos, with imagery back to the 1930s for many regions. The free version watermarks images but is fully usable for research. Compare the same plot of land across decades to spot former buildings, paths, and clearings.

Google Earth Pro (free)

The desktop version of Google Earth has a "historical imagery" slider that pulls aerial photos from the late 1990s onward for most US locations, with much older imagery for some areas. This is the single best tool for tracking how a piece of ground has changed in your lifetime — sometimes you'll catch the brief window when an old foundation was visible before the trees grew back over it.

USGS Earth Explorer

For deeper research, USGS Earth Explorer gives free access to high-resolution aerial photo archives going back to the 1930s, including unwatermarked NHAP (high-altitude) and NAIP (modern color) imagery. Slightly more friction than HistoricAerials but the original sources.

5. LIDAR for hidden features

LIDAR is the secret weapon of serious researchers. Aircraft-mounted lasers scan the ground millions of points per second and produce a high-resolution elevation model that can "see through" tree cover. A LIDAR hillshade image — rendered as if the sun were low across the bare ground — reveals features invisible to aerial photography:

• Old road traces grown over with forest
• Building foundations as rectangular depressions
• Mill races, dam abutments, and millponds
• Charcoal hearths in old iron-making regions
• Native earthworks and historic fortifications
• Plowed fields hidden under reforestation

In the US, the USGS 3D Elevation Program (3DEP) publishes LIDAR for most of the country. State GIS portals often have friendlier viewers — Pennsylvania, New York, North Carolina, and Vermont all have particularly good free LIDAR hillshade tools. Search "[your state] LIDAR viewer" to find yours.

Once you find a feature on LIDAR — say, a rectangular depression in the woods 200 yards from a known old farm — cross-reference it with historical topos and aerials to confirm it's a real old foundation and not a modern excavation. Then visit it on the ground.

6. Local archives and historical societies

The internet is most of what you need, but the best leads often live in places that haven't been digitized. Three categories are worth knowing:

County and town historical societies

Most US counties and many towns maintain a historical society with a small archive. Plat maps, manuscript histories, family papers, and photo collections often live there and nowhere else. Send an email saying you're researching a specific area; they're usually happy to help, and a 20-minute call often gives you locations no map will.

Newspaper archives

Chronicling America (Library of Congress) is a free searchable archive of historical US newspapers. Search a town name and "picnic," "fairgrounds," "blacksmith," "tavern" — you'll find references to event sites and businesses long forgotten. Newspapers.com is paid but vastly larger.

The David Rumsey Map Collection

davidrumsey.com is a free digital archive of over 100,000 historical maps from around the world, including county atlases, plat maps, railroad maps, and hand-drawn settlement maps that don't appear anywhere else online.

County GIS portals

Almost every US county runs a public GIS portal showing parcel boundaries, ownership, and zoning. Search "[county name] GIS" or "[county name] parcel viewer." This is how you go from "interesting spot on a map" to "I need to write to the Andersen family at 412 Old Mill Road for permission."

7. Permission and legality research

Before you set foot on a spot, confirm two things: who owns it and whether detecting is legal there. Quick rules of thumb:

• Private property — always requires the owner's permission. Use the county GIS to identify the parcel owner and send a polite written request. Mention that you fill every hole, share what you find, and carry insurance if you have it. Hit rate is low; the yes you do get is often a goldmine.
• National parks, national forests, national monuments, NPS seashores — generally prohibited under federal law (Archaeological Resources Protection Act). Don't.
• BLM and US Forest Service land — varies. Some areas allow incidental detecting for modern items; historic and archaeological areas are off-limits. Check the specific district.
• State parks — varies state by state. Some are open, some require permits, some prohibit it. Check the state parks department site.
• City and county parks — most common access. Often allowed with rules about restoring divots and avoiding monument areas.
• Schools, churches, fairgrounds (active) — always ask. Schools especially are a gray area and a phone call to the maintenance office is the right move.

For comprehensive federal-land rules, the NPS regulations on detecting (36 CFR 2.1) and your state's parks department page are the authoritative sources. Always go to the source rather than trusting forum posts — rules change, and "I read on Reddit it was fine" is not a defense.

8. Reading field signs on the ground

Once you've narrowed your research to a candidate site and confirmed access, walk the ground before you swing. Old human activity leaves lasting biological and physical traces that confirm you're in the right spot:

Plant indicators

• Lilac — almost always planted next to dooryards. A lilac in the middle of an open field marks a former house.
• Periwinkle / myrtle — a low evergreen ground cover commonly planted around old farmhouses and cemeteries. A patch in the woods often means a foundation is nearby.
• Daffodils, day lilies, peonies — perennials that persist for a century after planting. A line of daffodils in the woods often traces a former front walk.
• Asparagus — gone-feral asparagus marks former kitchen gardens.
• Apple trees in the woods — orchard remnants, often near old farms.
• Horse chestnut and unusual hardwoods — non-native ornamentals planted as shade trees by old houses.

Physical indicators

• Foundation stones — squared stones at right angles are a dead giveaway. Cut stone almost never occurs naturally.
• Rectangular depressions — collapsed cellars or dugouts.
• Stone walls — in New England especially, every stone wall ran along an old farm boundary or pasture. Hunts often start at wall corners.
• Brick scatter or coal clinker — surface artifacts at a former dooryard or chimney location.
• Worn paths and depressions — old footpaths and wagon tracks compress soil that takes a century to recover.

The strongest sites combine multiple signs: a square depression surrounded by lilac and ringed by stone walls, with a perennial bed of daffodils tracing the front walk. That site was a house.

9. A full research workflow

Here's the workflow most experienced detectorists use, condensed. Pick one candidate area and work through it end to end. The whole sequence takes about 45 minutes per spot once you're practiced.

1. Pin the area. Pick a square mile or so of ground that interests you — near an old town, a historic crossroads, or somewhere you've heard rumors.
2. Pull the oldest USGS topo on topoView. Note every building square, named place, school, mill, and crossroads structure. Capture screenshots overlaid with the modern map.
3. Cross-check Sanborn maps if it's near a town. Identify any building footprints inside the area. Note the use (hotel, store, dwelling).
4. Scrub HistoricAerials and Google Earth historical. Find any feature visible on older photos and gone today. Foundations, paths, clearings.
5. Check LIDAR if it's wooded. Look for rectangular depressions, old roads, and earthworks that aerial photos miss.
6. Look up the parcels in the county GIS. Identify owner names and addresses for any spot you'd need permission to hunt.
7. Confirm legality. If it's public land, check parks-department rules. If federal, default to "no."
8. Send permission requests. Polite, brief, mention restoring holes and offering to share finds.
9. Walk the ground. Confirm field signs match your map research. Pin the most promising sub-locations to hunt later.
10. Hunt and log. Keep a record of what each spot produced. Sites that look identical on paper can vary 10× in real productivity, and your log is how you learn the difference.

The first time through, this feels like a lot. By the third or fourth candidate area you'll have the rhythm down, and you'll start seeing patterns — the same kinds of spots produce the same kinds of finds across regions. That pattern recognition is the closest thing this hobby has to a superpower, and it's built one research session at a time.

FAQ

Pin your research, track your hunts

Download LuckyFind — free for iPhone and Android — to pin candidate sites, log finds with photos and notes, and overlay your past hunts on the map so you never re-walk old ground.