The Census Bureau estimates that in 1776, two-and-a-half million people lived in the 13 colonies which ultimately became the United States of America.

The first U.S. Census was begun in 1790 and 18 months later determined that approximately 4 million people were living in the United States. At the time, the largest city was Philadelphia, boasting a population of 42,000. In decreasing size were the major cities of the day: New York, Boston, Baltimore, and Charleston.

Source: U.S. Census Bureau