is a county located in the U.S. state of Texas, located in the southeastern part of the state near Galveston Bay. As of the 2010 Census, the population was 4,092,459, making it the most populous county in Texas and the third most populous county in the United States. Its county seat is Houston, the largest city in Texas and fourth largest city in the United States. The county was founded in 1836 and organized in 1837. It is named for John Richardson Harris, who founded the town of Harrisburg on Buffalo Bayou in 1826. According to a July 2018 Census estimate, Harris County's population had grown to 4,698,619, comprising over 16 percent of Texas's population.