US County Map Interactive
Explore all 3,143 US counties interactively with population, median income, land area, and state filter.
The US County Map Interactive is a cartographic web application that lets users visualize, analyze, and style all 3,143 United States counties and county equivalents. Explore demographic choropleth heatmaps (population, land area, population density), build custom color-coded sales territories, inspect Federal 5-digit FIPS codes (ANSI INCITS 31:2009), and export vector SVG and CSV datasets.
Interactive US County Map & Choropleth Explorer
Explore county choropleth heatmaps, paint custom territory groups, and export high-res vector maps.
Click on any county row in the directory below to spotlight its boundary, demographic rank, and FIPS code.
California Counties Directory (14 counties)
Click any county to highlight and view its demographics on the interactive basemap above.
| Color | County Name | FIPS Code | County Seat | Population | Land Area | Density | Actions |
|---|---|---|---|---|---|---|---|
| Los Angeles County | 06037 | Los Angeles | 9,721,138 | 4,058 sq mi | 2395.5 / sq mi | ||
| San Diego County | 06073 | San Diego | 3,276,208 | 4,207 sq mi | 778.8 / sq mi | ||
| Orange County | 06059 | Santa Ana | 3,151,184 | 791 sq mi | 3983.8 / sq mi | ||
| Riverside County | 06065 | Riverside | 2,458,395 | 7,206 sq mi | 341.2 / sq mi | ||
| San Bernardino County | 06071 | San Bernardino | 2,181,654 | 20,057 sq mi | 108.8 / sq mi | ||
| Santa Clara County | 06085 | San Jose | 1,877,592 | 1,290 sq mi | 1455.5 / sq mi | ||
| Alameda County | 06001 | Oakland | 1,628,997 | 739 sq mi | 2204.3 / sq mi | ||
| Sacramento County | 06067 | Sacramento | 1,585,055 | 965 sq mi | 1642.5 / sq mi | ||
| Contra Costa County | 06013 | Martinez | 1,155,677 | 716 sq mi | 1614.1 / sq mi | ||
| Fresno County | 06019 | Fresno | 1,015,190 | 5,958 sq mi | 170.4 / sq mi | ||
| San Francisco County | 06075 | San Francisco | 808,437 | 47 sq mi | 17200.8 / sq mi | ||
| Ventura County | 06111 | Ventura | 832,605 | 1,843 sq mi | 451.8 / sq mi | ||
| San Joaquin County | 06077 | Stockton | 779,233 | 1,391 sq mi | 560.2 / sq mi | ||
| Kern County | 06029 | Bakersfield | 909,235 | 8,132 sq mi | 111.8 / sq mi |
US County Map Technical Specifications & Standards
NAD83 / WGS84 (EPSG:4326)
Standard global ellipsoidal coordinate reference system
US Geodesics
Official federal FIPS identifiers and decennial demographic statistics
GeoJSON · KML · CSV · SVG
Compatible with QGIS, ArcGIS, Google Earth & CAD
100% Client-Side
Calculations run in-browser. Zero coordinate logging.
How to Use the US County Map Interactive
Follow this step-by-step procedure to execute precise spatial measurements and export results.
- 1Select a State and Exploration Mode: Choose any of the 50 US states from the dropdown menu or quick-filter pills (such as California, Texas, Florida, or New York), and toggle between "Thematic Heatmap" and "Custom Territory" modes.
- 2Analyze Thematic Choropleth Heatmaps: In Thematic Heatmap mode, select your preferred data metric (Total Population, Land Area in sq mi, or Population Density) to automatically render a 5-tier quantile color gradation across all counties in the state.
- 3Paint & Group Custom County Territories: In Custom Territory mode, select an active color swatch (Emerald, Blue, Crimson, Amber, Purple, Teal) and click individual counties on the map or table to assign custom territory categories.
- 4Inspect Metadata & Export Vector Assets: Click on any county to open the County Inspector Card with official FIPS codes, county seats, and population ranks. Click "Export SVG" for clean vector artwork or "Export CSV" for spreadsheet analysis.
Geodesic Precision vs. Competitor Mapping Approaches
Most legacy mapping utilities (such as CalcMaps and FreeMapTools) rely on planar Web Mercator projections or spherical approximations, causing significant mathematical distortion at higher latitudes. GeoMap Suite computes exact ellipsoidal geodesics on the WGS84 reference ellipsoid.
| Calculation Model | Mathematical Basis | Distortion on WGS84 | Standard Tools | Practical Application |
|---|---|---|---|---|
| Planar (Web Mercator) | Cartesian dx² + dy² | 10% to 200%+ error | CalcMaps / Simple map tools | Distorts drastically away from equator. Inaccurate for true distance. |
| Spherical Great-Circle | Haversine (R = 6,371 km) | Up to 0.5% (~5 km/1,000 km) | Basic Google Maps wrappers | Ignores Earth's polar flattening. Reasonable for rough estimates. |
| GeoMap Suite Ellipsoidal | Karney Direct/Inverse WGS84 | < 15 nanometers (<0.0001%) | GeoMap Suite | Geodetic surveying, maritime, flight paths & legal boundary analysis. |
Thematic Demographic Choropleth: California County Population Density
A state public health agency visualizes population density variations across California’s 58 counties.
Input Parameters
- State
- California (58 Counties)
- Mode
- Thematic Choropleth
- Metric
- Population Density (People / sq mi)
Computed Outputs
- Highest Density County
- San Francisco County (FIPS 06075): ~17,200/sq mi
- Lowest Density County
- Alpine County (FIPS 06003): ~1.6/sq mi
- Choropleth Distribution
- 5-tier quantile color gradient applied to all 58 counties
Step-by-Step Mathematical Process
- Load California county boundaries and Census ACS demographic data.
- Compute 5-tier quantile breaks for population density: Tier 1 (<50/sq mi) to Tier 5 (>2,000/sq mi).
- Shade San Francisco County (17,200/sq mi) and Los Angeles County (2,430/sq mi) in deep Tier 5 green.
- Shade Alpine County (1.6/sq mi) and Inyo County (1.8/sq mi) in light Tier 1 green.
Commercial Territory Mapping: Texas Regional Sales Hubs
A medical device distributor segments Texas counties into North, South, Central, and West regional sales territories.
Input Parameters
- State
- Texas (254 Counties)
- Mode
- Custom Territory Painter
- Colors
- Blue (North TX), Emerald (Central TX), Crimson (South TX), Amber (West TX)
Computed Outputs
- Custom Territories Defined
- 4 distinct color-coded commercial zones
- Total Counties Assigned
- Multi-county sales clusters across 254 Texas counties
- Export Format
- Vector SVG + CSV dataset
Step-by-Step Mathematical Process
- Select Texas in the interactive county map.
- Choose "Custom Territory" mode and select the Navy Blue swatch for Dallas, Tarrant, Collin, and Denton counties.
- Select the Emerald swatch for Travis, Williamson, and Bexar counties.
- Select the Crimson swatch for Harris, Fort Bend, and Galveston counties.
- Click "Export SVG" to save the customized vector territory map for corporate presentation slides.
Understanding Your Results & Practical Interpretation
Understanding Quantile Choropleth Breakpoints
Quantile classification divides sorted county values so that an equal number of counties fall into each of the 5 tiers. This guarantees high visual contrast across states with skewed distributions (like California or New York where one or two counties contain vast percentages of the population).
Federal 5-Digit FIPS Standardization
Every county in the map is indexed by its official ANSI 5-digit FIPS code. The first two digits represent the state (e.g. 06 for California, 48 for Texas), and the remaining three digits identify the specific county division.
Custom Territory Painter & Multi-County Grouping
In Custom Territory mode, users can click multiple counties with distinct color swatches to plan sales regions, election districts, franchise zones, or delivery corridors with instant visual feedback.
Vector SVG vs. Spreadsheet CSV Export
The "Export SVG" button generates scalable vector graphics suitable for Adobe Illustrator, Figma, Inkscape, or high-resolution printing. The "Export CSV" button produces a clean data table for Excel, R, or Python.
Practical Applications & Real-World Use Cases
Sales Territory & Franchise Boundary Design
Assign and visualize dealer territories, field service zones, and regional distributor quotas by painting contiguous county groups.
Academic Research & Classroom Presentations
Explore demographic patterns across US states, study urbanization trends, and export clean vector maps for reports and publications.
Supply Chain & Logistics Network Planning
Map regional distribution coverage, cross-dock zones, and delivery radius constraints across multi-county operating areas.
Mathematical Methodology & Geodetic Accuracy
US Census Bureau TIGER/Line & Quantile Choropleth Algorithms
County boundaries and demographic datasets are derived from the United States Census Bureau TIGER/Line cadastral database. Thematic heatmaps use a 5-tier quantile distribution algorithm that divides sorted county metrics into five equal-frequency statistical brackets.
Q_k = \left[ x_{\lfloor (k-1)N/5 \rfloor}, \, x_{\lfloor kN/5 \rfloor} \right] \quad \text{for tiers } k \in \{1,2,3,4,5\}Limitations & Boundary Conditions
- •Quantile breaks are computed per state to ensure maximum statistical contrast within each state’s unique demographic distribution.
- •Parishes in Louisiana and Organized Boroughs in Alaska are indexed as standard county equivalents.
- •Virginia’s independent cities are treated as county equivalents with distinct 5-digit FIPS codes.
Troubleshooting & Geographic Edge Cases
How do I switch between the automatic heatmap and manual county coloring?
Use the "Explorer Mode" toggle buttons on the toolbar to switch between "Thematic Heatmap" (automatic 5-tier color gradation) and "Custom Territory" (click to color counties manually).
How do I clear all custom colors I have painted?
In Custom Territory mode, click the "Clear" button next to the color swatches to reset all counties back to their default neutral shade.
Can I download the SVG map and edit it in graphics software?
Yes. Click the "Export SVG" button to download a clean, standards-compliant SVG file that can be opened and edited in Figma, Adobe Illustrator, Inkscape, or any web browser.
Why are Virginia independent cities listed separately?
Under Virginia state law, 38 independent cities (such as Richmond, Alexandria, and Virginia Beach) are legally independent of any county and are classified as county equivalents by the federal government.
Frequently Asked Questions
An interactive US county map is a digital cartographic tool that allows users to explore, filter, color, and analyze all 3,143 counties and county equivalents across the United States with real-time demographic and geographic statistics.