Latitude and longitude explained

Latitude: north and south

Picture a line from the center of the Earth to your location. Latitude is the angle between that line and the plane of the equator. The equator is 0°, the North Pole 90° N and the South Pole 90° S. Lines of equal latitude are called parallels because they never meet.

Strictly, GPS uses geodetic latitude, measured from a line perpendicular to the WGS84 ellipsoid rather than from the Earth's center. The two differ by up to about a fifth of a degree in the middle latitudes, which is why a degree of latitude is not quite the same length everywhere. The miles per degree guide has the numbers.

Longitude: east and west

Longitude is the angle east or west of the prime meridian, the line from pole to pole that passes through Greenwich, England. Lines of equal longitude are meridians, and they all meet at the poles. East longitudes run to 180° E and west longitudes to 180° W, and the two meet on the opposite side of the planet near the International Date Line. Every US state lies west of Greenwich, so US longitudes are written with a W or a minus sign, apart from the far end of Alaska's Aleutian Islands, which crosses 180°.

How coordinates are written

The same point can be written several ways. Denver's capitol coordinate on this site is 39.739, -104.985 in decimal degrees, 39°44'20.40"N 104°59'6.00"W in degrees, minutes and seconds, and 39°44.3400'N 104°59.1000'W in degrees and decimal minutes.

Convention puts latitude first. GeoJSON and many programming libraries put longitude first because it plays the role of x on a chart. When a pair of US coordinates looks wrong, check the order: a latitude can never exceed 90, and every longitude in the contiguous states is negative. The GPS coordinate converter reads any of these formats.

The northernmost and southernmost capitals

Juneau, AK is the northernmost capital at 58.30° N and Honolulu, HI the southernmost at 21.31° N. In the contiguous states, Olympia, WA is farthest north at 47.04° and Austin, TX farthest south at 30.27°. From west to east, the contiguous range runs from Salem, OR at 123.03° W to Augusta, ME at 69.78° W.

All 51 capitals from north to south

Places on the same latitude

Two places on the same parallel are the same distance from the equator, so on any given date they get almost the same number of hours of daylight, even if their clocks show different sunrise times. The cities on the same latitude tool lists US towns and world cities along any parallel, and the day length guide shows how latitude sets the hours of daylight.

Signs and hemisphere letters

Decimal degrees use signs: north and east are positive, south and west negative. Degree, minute and second notation uses letters instead. So Denver's 39.739, -104.985 becomes 39.739° N, 104.985° W. Never mix the two: -104.985° W is a double negative that some software reads as east. Pick one style for a whole file and state it in the column header.

Finding the coordinates of a place

The latitude and longitude finder below returns the coordinates of any address or map click in decimal degrees, with the other formats alongside. For counties, each county page on this site lists the Census internal point in every format, and each state page shows the capital's coordinates.