Where the 100 mile radius shows up
- The 100-Mile Diet. The local-food idea popularized by Alisa Smith and J.B. MacKinnon’s 2007 book of the same name: eat only food grown within 100 miles of home. Draw the circle to see which farms and growing regions qualify.
- Subpoenas. Federal Rule of Civil Procedure 45 generally limits where a subpoena can require someone to attend to within 100 miles of where they live, work, or regularly do business in person.
- Border enforcement. U.S. regulations define a “reasonable distance” from the border for some immigration enforcement as 100 air miles from any external boundary, including coastlines. The ACLU estimates that about two-thirds of the U.S. population lives within that zone.
- Regional planning. Distribution centers, regional offices, and hospital networks often think in 100 mile service regions.
Air miles and statute miles
Some rules say “air miles.” In U.S. transportation regulations an air mile is a nautical mile of 6,076 feet, about 15 percent longer than a statute mile. A 100 air-mile radius is therefore about 115 statute miles. To map air miles exactly, choose nautical miles in the unit menu, or see the 150 air-mile radius map used for truck driver hours-of-service rules.
A 100 mile radius in numbers
| Radius | 160.9 km · 86.9 nautical miles · 528,000 feet |
|---|---|
| Diameter | 200.0 miles · 321.9 km |
| Circumference | 628.3 miles · 1,011 km |
| Area | 31,414 sq mi · 81,363 km² |
| Area in land units | 20,105,124 acres · 8,136,255 hectares |
Area and circumference are calculated on a spherical Earth, so very large circles are slightly smaller than πr² suggests.
How long does it take to cross a 100 mile radius?
These times cover the straight-line distance from the center to the edge at a steady speed. Real routes are longer: road networks usually add 20 to 40 percent to the straight-line distance, more where rivers, hills, or coastlines force detours.
| Way of travel | Center to edge | With a 30% detour |
|---|---|---|
| Walking (3 mph / 5 km/h) | 1.4 days | 1.8 days |
| Cycling (12 mph / 19 km/h) | 8 h 20 min | 10 h 50 min |
| Driving on city streets (25 mph / 40 km/h) | 4 h 0 min | 5 h 12 min |
| Driving on highways (60 mph / 97 km/h) | 1 h 40 min | 2 h 10 min |
What a 100 mile radius covers in major cities
Places with at least 15,000 residents inside a 100 mile circle drawn from each city’s central reference point, using GeoNames data. Counts include city districts listed separately.
| Center | Places inside | Largest places inside |
|---|---|---|
| New York CityNew York City Hall in Lower Manhattan | 424 | Brooklyn (5.2 mi), Queens (9.1 mi), Philadelphia (80 mi) |
| Chicagothe Loop | 218 | Milwaukee (81 mi), Aurora (36 mi), Rockford (80 mi) |
| Los AngelesLos Angeles City Hall | 235 | Long Beach (20 mi), Anaheim (24 mi), Riverside (49 mi) |
| DallasDowntown Dallas | 72 | Fort Worth (31 mi), Arlington (18 mi), Plano (18 mi) |
| LondonCharing Cross | 406 | Leicester (89 mi), Coventry (86 mi), Islington (2.3 mi) |
| Paristhe Hôtel de Ville | 299 | Marne La Vallée (13 mi), Paris 15 Vaugirard (2.6 mi), Reims (81 mi) |
Earth’s curvature at 100 miles
At this size the map projection starts to matter. Web maps stretch areas toward the poles, so a true 100 mile circle in Canada or northern Europe looks taller than one near the equator. The tool draws the circle from real distances on a spherical Earth, which is why it can look slightly egg-shaped on screen at high latitudes. Area and circumference are calculated on the sphere too.
Related maps: 50 mile radius · 150 air-mile radius · find cities within a radius