100 Mile Radius Map

The size of a 100-mile radius

A 100-mile radius is a regional circle: 200 miles across, about 628 miles around, and roughly 31,416 square miles (81,370 km²) inside. That is about the size of South Carolina, or of Maine's land area. It is sixteen times the area of a 25-mile circle and four times that of a 50-mile circle, so it no longer describes a city or a metro area. It describes a region.

The map above starts with a 100-mile circle around downtown Atlanta. It takes in Athens, Macon and Columbus, Georgia, crosses into Alabama, Tennessee and South Carolina, and stops just short of Chattanooga. Move the center by searching any place, clicking the map, or using your current location.

How to draw a 100-mile radius around any place

1. Pick a center: type a city, address or landmark and press Center Map, or click the map. “Use Current Location” draws 100 miles from where you are.
2. Keep 100 miles or switch to kilometers (a 100 km circle is a much smaller 62-mile radius, so check the unit).
3. Zoom out with the map controls to see the whole circle and the states it touches. Area, perimeter and diameter are shown below the map.

Smaller rings have their own pages: the 25-mile radius map for local service areas and the 50-mile radius map for commuting distance. The radius map tool takes any value up to 3,000 miles.

How far is 100 miles by car?

A point on the edge of the circle is 100 miles away as the crow flies. By road it is usually 115 to 140 miles, and in mountainous country or around large bodies of water it can be much more. Typical travel times:

• Mostly interstate: about 1 hour 45 minutes to 2 hours 15 minutes.
• US and state highways through small towns: 2 1/2 to 3 hours.
• Mountain roads or ferry crossings: 3 hours or more.

That makes a 100-mile radius a good working definition of a day trip: far enough to feel like an outing, close enough to drive there and back on the same day with time to spend at the destination. For a map of what you can actually reach in two hours, use the drive-time map.

City pairs about 100 miles apart

Great-circle distance between city centers; New York to Philadelphia is included as a shorter reference.

Surprised that New York and Philadelphia are only about 80 miles apart? Distances between the big Northeast cities are shorter than most people guess, because the drive on I-95 through New Jersey adds detours and traffic. Check any pair with the as-the-crow-flies distance tool.

Reasons to map a 100-mile radius

Regional distribution and sales

A warehouse can usually reach every customer within 100 miles with same-day or next-morning truck delivery, so distributors use the circle to decide where a new depot would add coverage. Regional sales managers use it to size territories that one rep can drive in a day. Plot your customer list with the multiple-address map and compare it with the circle.

Day trips and weekend travel

“Things to do within 100 miles” is a classic way to plan a getaway. Center the circle on home, then look for parks, lakes and towns inside it; the nearest national park finder tells you whether one falls inside.

Ham radio and line of sight

Radio amateurs use 100-mile circles to visualize repeater coverage and contest contacts. Whether two stations 100 miles apart can talk on VHF or UHF depends on antenna height: with the usual 4/3-Earth refraction rule, the radio horizon is about 1.41 × √(height in feet) miles, so two antennas would each need to be roughly 1,250 feet above the terrain to see each other over 100 miles of flat ground. In practice such contacts rely on hilltops, tropospheric ducting or HF bands. Try heights in the horizon distance calculator.

Rules written in 100-mile terms

Several US rules use exactly this distance. Federal Rule of Civil Procedure 45 generally limits a subpoena to attend a trial, hearing or deposition to within 100 miles of where the person lives, works or regularly does business in person. Federal regulations define the “reasonable distance” from an external border, within which Border Patrol has certain extra search authority, as 100 air miles. And the “100-mile diet” local-food movement counts food grown within the circle. A map helps you see who or what is inside; it does not answer the legal question for you.

100 miles in perspective

One hundred miles is about 1.45 degrees of latitude (a degree of latitude is roughly 69 miles), or 160.9 kilometers. On foot it is a very long walk: more than 30 hours at a steady 3 mph, which is why 100-mile ultramarathons take most finishers a full day or longer. By bicycle it is a “century” ride, a classic one-day goal for recreational cyclists.

A 100-mile circle covers about as much land as 28 average US counties, and it often spans three or four states. Around the geographic center of the contiguous United States near Lebanon, Kansas, the circle reaches well into Nebraska; around Chattanooga, Tennessee it takes in parts of Georgia, Alabama and North Carolina. Run the tool around your own town and count the states it crosses.

Choosing the center

At this scale the choice of center matters more for a city than for a single address: moving the center from one side of a large metro area to the other shifts the edge by 30 miles or more. Common choices are:

• A street address for a business, warehouse or home: precise and unambiguous.
• City hall or downtown when a rule mentions a city by name.
• The geographic center of a group of places, when you are choosing a meeting point or depot location for many people. The geographic center finder computes it on the globe, and the halfway point tool does the same for two places.

Whichever you pick, note its coordinates next to your result. A radius without a precisely stated center is easy to argue about and hard to reproduce later.

ZIP codes within 100 miles

A 100-mile circle around a major city typically holds 200 to 800 ZIP codes; around New York City it holds almost 1,800, taking in both Philadelphia and Hartford. In the rural West it may hold only a few dozen. The counts below use the center point of each 2020 Census ZIP Code Tabulation Area.

For the complete list around your own center, with distances and CSV export for mail campaigns or territory planning, open find ZIP codes in a radius and set the distance to 100 miles. The cities in a radius tool gives the same answer at town level.

Accuracy at 100 miles: curvature and projection

At 100 miles the Earth's curvature starts to matter for drawing, though not for distance. The circle here is geodesic, computed point by point on the WGS84 ellipsoid, so its edge is exactly 100 surface miles from the center. On the Web Mercator base map, which stretches north–south distances more the farther you go from the equator, the circle appears slightly egg-shaped at high latitudes. A circle drawn with a fixed pixel radius on a flat map would be wrong by several miles at the top and bottom.