What is Longitude?

Longitude works the same way as latitude, but the angular distances are measured east and west of the prime meridian (which marks the 0-degrees longitude line that passes through Greenwich, England, without even disturbing traffic).

• When you travel east from the prime meridian, the longitude increases to 180 degrees.
• As you go west from the prime meridian, longitude also increases to 180 degrees. (The place where the two 180-degree longitudes meet is known as the International Date Line.)
• In the Eastern Hemisphere (which is east of the prime meridian to 180 degrees east), the longitude is given in degrees east.
• In the Western Hemisphere (which is west of the prime meridian to 180 degrees west), longitude is expressed in degrees west. One degree is actually a pretty big unit of measure. One degree of latitude or longitude is roughly equal to 70 miles.

Degrees are composed of smaller, fractional amounts that sound like you’re telling time.

• Degree: A degree comprises 60 minutes. One minute is about 1.2 miles.
• Minute: A minute is composed of 60 seconds.
  
• One second is around .02 miles.

These measurement units are abbreviated with the following symbols:

• Degree: °
• Minute: ‘
• Second: “

If you use minutes and seconds in conjunction with degrees, you can describe a very accurate location.
These distances are measured at the equator. At higher latitudes, the distance between longitude units decreases. The distance between latitude degrees is the same everywhere.
If you are using latitude and longitude to locate Dillon Falls on a map of the Deschutes River in Oregon, its coordinates are
43° 57’ 29.79” N 121° 24’ 34.73” W

That means that Dillon Falls is

• 41 degrees, 57 minutes, and 29.76 seconds north of the equator
• 121 degrees, 24 minutes, 34.73 seconds west of the prime meridian