Fort Lyon was constructed south of a city whose population was what in the census of 2010?
Fort Lyon (Virginia): Fort Lyon (usually Camp Lyon in Northern records) was a timber and earthwork fortification constructed south of Alexandria, Virginia as part of the defenses of Washington, D.C. during the American Civil War. Alexandria, Virginia:  As of the 2010 census, the population was 139,966, and in 2016, the population was estimated to be 155,810.
139,966