Alexandria is an independent city in the Commonwealth of Virginia in the United States. As of the 2010 census, the population was 139,966, and in 2016, the population was estimated to be 155,810. Located along the western bank of the Potomac River, Alexandria is approximately 7 miles south of downtown Washington, D.C.Like the rest of Northern Virginia, as well as Central Maryland, modern Alexandria has been influenced by its proximity to the U.S. capital. It is largely populated by professionals working in the federal civil service, in the U.S. military, or for one of the many private companies which contract to provide services to the federal government. One of Alexandria's largest employers is the U.S. Department of Defense. Another is the Institute for Defense Analyses. In 2005, the United States Patent and Trademark Office moved to Alexandria, and in 2017, so did the headquarters of the National Science Foundation.The historic center of Alexandria is known as "Old Town".