APG is a United States Army installation established in 1917 just six months after America entered World War I. Essentially a city-within-a-city, the base was home to more than 3,000 people and 800 families at the time of the 2000 census. Composed of more than 72,000 acres that span both Aberdeen and Edgewood, APG continues to be the oldest active proving ground primarily used to test ordinance, firearms and ammunition. This is a secured base and requires visitors to show valid identification and vehicle registration before entry is granted. Gates are monitored 24 hours per day.