This letter to the editor takes a newspaper to task for describing Jacksonville, Fla., as a medium-size city. The reader argues that Jacksonville's population makes it the largest city in Florida and the 13th largest in the United States. The Wikipedia entry on Jacksonville agrees with him.

Does the letter writer have a point? Not really. He's using a poor way to rank cities by population: the number of people living within city limits. Some cities, of course, have more land area than others. That's especially true for Jacksonville, which has an unusual merged city-county government. That makes Jacksonville exceptionally large geographically.

A better way to rank populations of cities is to look at metro area: a city and its suburbs. (You can read the technical definition here.) By that measure, Jacksonville is No. 45 in the United States, just ahead of Richmond, Va. Within Florida, it ranks behind Miami, Tampa-St. Petersburg and Orlando.

By that standard, Jacksonville is a medium-size city, so the newspaper's description was correct. The letter writer and Wikipedia are wrong.