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Map CSV Data by U.S. County
Join CSV or TSV values to official county FIPS, review unmatched and duplicate rows, and export a county choropleth with a legend.
Input & limits
A county FIPS column and a finite numeric value column. County names alone are not matched. Covers 3,222 county equivalents including Puerto Rico.
What you download
Joined county polygons, a data CSV, diagnostics, a method report and an SVG or PNG map with title and legend.
How to use
- Paste a table, choose a CSV/TSV file or load the real ACS population example.
- Select the FIPS and value columns, resolve duplicate rows and choose classification and colors.
- Build the map, review join diagnostics, then export the map or data.
Frequently asked questions
Are leading zeros required?
Five-digit FIPS strings are preserved. Short numeric codes can be padded explicitly by the parser; invalid or unknown county codes are reported.
Are duplicate values silently overwritten?
No. Choose an explicit duplicate policy: reject, sum or use the last valid value. Invalid, missing and unmatched rows are reported separately.