Washington County is a county located in the U.S. state of Utah. As of the 2010 census, the population was 138,115, making it the fifth-most populous county in Utah. Its county seat and largest city is St. George. The county was created in 1852 and organized in 1856. It was named for the first President of the United States, George Washington. Washington County experienced the fifth highest job-growth rate in the United States at one point. Washington County comprises the St. George, UT Metropolitan Statistical Area.