On August 2, 1790, the United States completed its first Constitutionally-mandated census.  The total population of the 13 colonies was 3,929,214 people (almost 700,000 of which were slaves).  There are now estimated to be 304,059,724 people living in the 50 United States.

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Fact of the Day
On August 2, 1790, the United States completed its first census of its population. Population then: 3,929,214
Population now: 304,059,724