Why?
I've been developing an embedded device intended for offline use that will use GPS to synchronize your computer so that you can have a digital activation for Parks On The Air. I thought it would be neet if it could let you know what POTA reference you are in as well. That began my journey to explore and understand how tile-indexed geospatial databases work.
The embedded project is still underway. I thought it would be fun to surface the geospatial search features in a simple database. So here we are.
And by the way, the databases (there are two) need to fit inside of 16MB SPI NOR flash, and queries need need to fit within the limited memory constraints of the embedded system.
What it does
Nearest POTA finds the closest eligible Parks On The Air reference points to a latitude and longitude. Enter coordinates or allow your browser to provide a location, and the site returns the nearest 20 references with their distances and local times. If applicable, it also attempts to determine the US county your search originates in. In some cases (near boarders) it will return more than one county.
How lookup works
The site uses two compact, read-only geospatial databases. POTADB uses a sparse one-degree geographic tile index to find candidate Parks On The Air™ reference points, calculate great-circle distances, and rank the closest results. The displayed point is a POTA reference point; it is not a park boundary, an access point, or a guarantee that you are inside the park.
CountyDB uses a separate one-degree tile index and county-boundary containment test to identify the county or county-equivalent at the submitted location. Its compact boundary geometry has a small guard area around transformed county lines. Within that guard, the site lists the plausible counties instead of choosing one arbitrarily.
Each reference local time is calculated from its IANA timezone and the database-compiled time-zone transition rules, including daylight-saving changes and non-hour UTC offsets.
Data and updates
POTADB is built from publicly available POTA reference data and time-zone data. CountyDB is built from the U.S. Census Bureau's 2025 TIGER/Line county source. Both are bundled snapshots: updates rebuild and redeploy the database files, so live POTA references or Census source revisions may change before this site reflects them.
The county result is a convenience feature. It does not establish a legal boundary determination or a location for a POTA reference.
Privacy
Browser location is requested only when you select the browser-location option. You can instead enter coordinates directly. The selected coordinates are placed in the page address after a lookup so that a result can be shared or reopened.