Dallas County is a county located within the US State of Texas. It is part of the Dallas-Fort Worth-Arlington Metropolitan Area. Its population, based off of the 2010 US Census, is currently 2,368,139. Its county seat is the City of Dallas. The Dalas County Public Works plans, develops, implements, and administers regional transportation projects within the county. Dallas County also operates the Dallas County Sheriff's Department which provides law enforcemet services to the county.