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. According to the 2007 US Census Estimate, Pine Bluff now has a population of 50,667 The University of Arkansas at Pine Bluff is located here. Pine Bluff is also the home of the Pine Bluff Arsenal, a major site for the demolition of chemical weapons.