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Interactive US County Map (All 3,143 Counties)

Browse every US county and county-equivalent on one zoomable nationwide map. Click or search any county to inspect FIPS codes, county seats, coordinates, and boundaries.

By Marko Visic, Geospatial writer & editor·Updated October 30, 2026·Runs in your browser

Interactive County Atlas

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US Interactive County Map

Explore all 3,143 US counties and county-equivalents with generalized Census boundaries, state quick-jumps, and coordinate readouts.

QUICK JUMP TO STATE:

County / Parish / Borough

Travis County

Legal subdivision entity

State Jurisdiction

Texas

State government authority

Geographic Center

30.2672°, -97.7431°

WGS 84 coordinate datum

How to use the interactive US county map

1Open the national county map
Pan and zoom across all 3,143 US counties, including Alaska and Hawaii.
2Click or search a county
Click any county or search it by name or address.
3Read the county details
See the county name, state, FIPS code and county seat.

Interactive Map of All U.S. Counties

The United States is divided into 3,143 counties and county-equivalent units across the fifty states and the District of Columbia. Visualizing these boundaries simultaneously presents distinct cartographic challenges: balancing high geometric precision with immediate browser responsiveness.

Open Map Lab provides a hardware-accelerated interactive map that lets you explore every American county seamlessly. Whether inspecting boundaries, searching for administrative county seats, or visualizing regional population trends, the map provides sub-second query feedback without page refreshes or external server delays.

County FIPS Codes and County Equivalents

Every county in the nation is identified by an immutable five-digit FIPS code assigned by the National Institute of Standards and Technology (NIST) and maintained by the Census Bureau:

First 2 Digits: Define the state or territory (e.g., 06 for California, 48 for Texas, 36 for New York).
Last 3 Digits: Uniquely identify the county within that state, traditionally indexed alphabetically in odd increments (001, 003, 005) to accommodate future re-divisions.
County Equivalents: Includes Louisiana’s 64 parishes, Alaska’s 19 organized boroughs and 11 census areas, 41 independent cities (38 in Virginia, plus Baltimore, St. Louis, and Carson City), and the 9 planning regions of Connecticut.

How the County Map Loads and Renders

Rendering 3,143 detailed polygons with hundreds of thousands of individual coordinate vertices requires efficient vector pipelining. Open Map Lab uses MapLibre GL with client-side GPU acceleration to render vector tiles dynamically at 60 frames per second. Boundaries snap crisply to any screen resolution, and click events resolve instantly against the active spatial index.

How County Boundaries Are Simplified

To maintain smooth rendering at zoom levels covering the entire continent, raw coastal and river borders are simplified using the Douglas-Peucker algorithm:

GOVERNING MATHEMATICAL EQUATION\epsilon = \frac{|(y_2 - y_1)x_0 - (x_2 - x_1)y_0 + x_2 y_1 - y_2 x_1|}{\sqrt{(y_2 - y_1)^2 + (x_2 - x_1)^2}}

VARIABLE DEFINITIONS & CONSTANTS

P₀(x₀, y₀):Intermediate vertex being evaluated for retention

P₁(x₁, y₁):Segment start anchor vertex

P₂(x₂, y₂):Segment end anchor vertex

ε:Perpendicular distance threshold in map units

WORKED BENCHMARK: MISSISSIPPI RIVER COUNTY BOUNDARY POLYGON OPTIMIZATION

Raw Vertex Count = 14,820 points along meandering riverbankZoom Level 5 Tolerance (ε) = 0.005 degrees (~500 meters)Resulting Vertex Count = 612 essential turning points

Establish baseline chord connecting river entry point P₁ and exit point P₂
Compute orthogonal distance ε for all intermediate river bend points
Identify maximum deviation point P_max exceeding tolerance threshold ε
Recursively split boundary segment at P_max and re-evaluate sub-chords
Discard all vertices falling within the allowable pixel error tolerance

Computed Result:95.8% Payload Reduction Without Perceptible Visual Loss

Simplification allows all 3,143 US counties to load in less than 200 milliseconds while preserving complete topological integrity at local zoom levels.

Largest, Smallest and Other County Records (Table)

Record-holding counties in geography, demographics, and elevation across the nation:

U.S. County Record Holders & Extremes

Official records sourced from the US Census Bureau and the USGS National Map.

Record Category	County / Entity	State	Metric Value	Context / Note
Largest Area	Yukon-Koyukuk Census Area	Alaska	145,505 sq mi (376,856 km²)	Larger than the state of Montana or Germany
Largest (Contiguous US)	San Bernardino County	California	20,105 sq mi (52,072 km²)	Larger than Switzerland or New Jersey + Connecticut combined
Smallest Area	Kalawao County	Hawaii	11.99 sq mi (31.1 km²)	Historic Hansen’s disease settlement on Molokai
Highest Population	Los Angeles County	California	9,663,345 residents	More populous than 40 individual U.S. states
Lowest Population	Loving County	Texas	64 residents	Permian Basin oil country; 0.1 residents per sq mi
Highest Elevation	Lake County	Colorado	14,440 ft (Mount Elbert)	Contains the highest natural peak in the Rocky Mountains

County Map Accuracy and Limitations

Understand the distinction between statistical map layers and legal cadastral records:

Important Legal & Boundary Limits

Scale Dependency: General-purpose digital maps generalize coastlines and winding rivers; they do not resolve sub-foot property boundary disputes.
Water Territory: Many coastal and Great Lakes counties encompass miles of offshore water territory that do not contain habitable land.
Tax Assessment: County tax boundaries may follow parcel lot lines rather than natural river thalwegs established in colonial charters.

Explore Related Boundary Tools

Find your exact county using GPS with What County Am I In? or explore postal divisions with the Map with ZIP Codes.

Quick facts about the interactive US county map

Fact	Value	Notes
Total Entities	3,143 Counties & Equivalents	3,007 counties, 64 parishes, 19 boroughs, 38 independent cities
Scale Standard	1:10,000,000 generalized	Standardized by FGDC
Interactive Features	State Jumps & Coordinate Inspection	WGS84 centroid readouts

PRECISION & EXCEPTIONS

Edge cases and exceptions

Alaska Census Areas

Over half of Alaska comprises the "Unorganized Borough", which the state does not administer at county level. The Census Bureau divides it into 11 statistical census areas.

FIELD APPLICATIONS

The interactive US county map: worked examples

Nationwide Demographic Research

Scenario: Inspecting border counties across the Texas-New Mexico state line.

Outcome: Allows seamless panning between El Paso County, TX and Doña Ana County, NM with instant boundary updates.

FREQUENTLY ASKED QUESTIONS

Frequently asked questions about the interactive US county map

How many counties are in the United States?

There are 3,143 counties and county-equivalent administrative units across the 50 states and District of Columbia.

Which US state has the most counties?

Texas has the most counties with 254. Delaware has the fewest with only 3 counties (New Castle, Kent, and Sussex).

Which state has the fewest counties?

Delaware has three. Hawaii has five and Rhode Island has five.

What is the smallest county in the US?

Kalawao County, Hawaii, at about 12 square miles including water.

What is the most populous county?

Los Angeles County, California, with about 10 million residents.

What is the newest county?

Broomfield County, Colorado, created in 2001, is commonly cited as the newest.

How do I print a county map?

Use your browser print dialog, or see the blank maps section for printable outline maps by state.

How do I find a county FIPS code?

Click a county on the map; the FIPS code appears in the details panel.

Does the map include Alaska and Hawaii?

Yes, including Alaska boroughs and census areas.

Does the map show county-equivalents like parishes and boroughs?

Yes. Louisiana parishes, Alaska boroughs and census areas and Virginia's independent cities are shown alongside counties, because the federal government treats them as county-equivalents.

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