How to Locate Cities by Latitude

The Equator circles the Earth midway between the North and South Poles and carries the value of 0 (zero) degrees latitude. Lines of latitude from the Equator extend north and south toward the Poles, with each latitude line signifying an angular distance in degrees, minutes, and seconds. Latitude lines north of the Equator are described as positive degrees (+30 degrees) or degrees north (30 degrees north) whereas latitudes south of the Equator are depicted as negative degrees (-30 degrees) or degrees south (30 degrees south).

• 1

  Examine the map that will be used to locate the cities. Note that lines of latitude north or south of the Equator will be assigned degrees that increase in number from 0 degrees at the Equator to 90 degrees at each Pole. Also note that if you break down the Earth's circumference (25,000 miles) into 360 segments, then each segment/degree is separated by a distance of approximately 69 miles. If a city's latitude has a negative number or is followed by the word "south," it will be located south of the Equator whereas a positive number or the word "north" indicates the city will be found north of the Equator.

• 2

  Examine the map to see whether it has certain cities notated with degrees, minutes, and seconds. (Don't worry if these notations don't exist.) Be aware that each degree is broken down into 60 minutes so that for each minute added on behind the degree reading, the cities will be located a bit farther north or south of the degree line. The city of Houston, Texas, for instance, is located at +29 degrees 45' (minutes), meaning that Houston is located 3/4 of a latitude north of the 29th parallel or 1/4 of a latitude south of 30 degrees north.

• 3

  Note that each minute of latitude can be further broken down into 60 seconds, in order to place a city more precisely on a map, either north or south of a degree marker. Looking at Houston, Texas, again, observe that the latitude is 29 degrees 45' (minutes) 26" (seconds), placing the city almost another 1/2 minute farther north of the 29th parallel and even closer to 30 degrees north. (Keep in mind that minutes and seconds, when used with latitude and longitude, do not refer to time but to degrees of arc.)

• 4

  Determine whether the city is north or south of the Equator. Locate the latitude, minute, and second anywhere on the map, then follow it east or west until the city is located. Alternately, starting with a city, determine if it's in the northern or southern hemisphere. Then ascertain the nearest line of latitude south of the city (if north of the Equator) or north of the city (in the southern hemisphere). Minutes and seconds of arc can be approximated by the city's proximity to the next line of latitude north or south of the city.