Jefferson County is a U.S. county located in the U.S. state of Arkansas. Its population was 84,278 at the 2000 United States Census. It is included in the Pine Bluff Metropolitan Statistical Area. Jefferson County's county seat and largest city is Pine Bluff. Jefferson County is Arkansas's 21st county, formed on November 2, 1829 from portions of Arkansas and Pulaski counties, and named for Thomas Jefferson, third President of the United States.
Pine Bluff is the largest city and county seat of Jefferson County, Arkansas, United States. It is also the principal city of the Pine Bluff Metropolitan Statistical Area and part of the Little Rock-North Little Rock-Pine Bluff, Arkansas Combined Statistical Area. According to 2006 Census Bureau estimates, the population of the city is 52,693, ranking it as the seventh most populous city in the state.