Oklahoma City (OKC) was established on April 22, 1889, when over 10,000 people participated in the Land Run and settled in what is now downtown Oklahoma City. OKC is the most populated city in the state and the 29th largest City in the U.S. At 621.2 square miles, Oklahoma City is in the top five largest cities in the country in terms of geographic area. The City spreads into four counties: Oklahoma, Canadian, Cleveland and Pottawatomie.