Detector Maps
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Open the mapPut your own maps on the modern landscape
Found a county atlas page, an estate plat, or an old aerial that isn't in any app? Upload it as a JPEG, PNG, TIFF, PDF, or JP2 and pin it over today's map with drag, resize, rotate, opacity, and skew controls. It's saved as a tiled overlay in My Maps, synced between your phone and the desktop web app.
Import any map you can scan
That county atlas plate, the estate plat from the courthouse, the fairgrounds photo from a local history book — upload it as JPEG, PNG, TIFF, PDF, or JP2 and it lands straight in the georeferencer. If you can get it into a file, you can get it on the map.
Drag, rotate, and skew it into place
Grab the handles and line your map up against modern imagery — drag, resize, rotate, with an opacity slider to check the fit, plus an advanced skew mode for old surveys that never sit square. Once it locks in, it becomes a live tiled overlay in My Maps, synced across mobile and web and ready offline in the field.
Cross-platform georeferencer is a Pro feature.
9,500+ maps already pinned down
No scan of your own? Browse 9,500+ georeferenced historical maps from the David Rumsey Map Collection, searchable by region, era, and type — old town plans, military, mining, roads, coastal, and surveys. Pick one and it overlays with its own opacity control, no lining up required.
Courtesy of the David Rumsey Map Collection.
Four ways detectorists use it
Overlay a county atlas page
Snap or scan a page from an 1870s county atlas showing farmsteads, schoolhouses, and churches that vanished generations ago. Line up the section roads with today's map and every marked homesite becomes a spot you can actually walk to.
Square up a crooked plat photo
Photos of estate plats and courthouse records are almost never shot perfectly flat, so plain rotate-and-resize leaves them warped against the map. Skew mode lets you pull each corner independently until the boundary lines sit true.
Compare old aerials with today
Vintage aerial photos capture field boundaries, orchard rows, and building footprints that were leveled decades ago. Slide the opacity down and you can see exactly which modern feature sits where the old barn stood.
Carry the same overlay everywhere
Do the careful positioning on the big screen at home, then open the identical overlay on your phone when you arrive on site. Uploads live in My Maps and sync across your devices — nothing gets redone in the field, and Pro adds the desktop web app.
Everything included
The questions we get most
What file types can I upload?
JPEG, PNG, TIFF, PDF, and JP2 all work. That covers phone photos of atlas pages, courthouse scans, and the big JP2 files government archives often hand out. If a source gives you a choice, grab the higher-resolution version — it holds up better when you zoom in.
How do I line an old map up accurately?
Find features that exist on both maps — road intersections, section corners, river bends, rail lines — then drag, resize, and rotate until two or three of them lock in. If your source is a photo taken at an angle, switch to skew mode and pull the corners until the straight lines actually run straight. The opacity slider lets you check your work as you go.
Where do my uploaded maps live?
Every upload is saved as a tiled overlay in My Maps on your account, and it syncs between the mobile app and the desktop web app. You toggle it on and off like any other layer and set its opacity per map.
Do I need any GIS experience?
No — it's drag, resize, rotate, and skew with your mouse or fingers, closer to arranging a photo than running mapping software. Most people have their first atlas page positioned in a few minutes. The real skill is just spotting a couple of landmarks that appear on both the old map and the new one.
The other layers
Historical map imagery courtesy of the David Rumsey Map Collection
Your old map belongs in the field
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