▁District ▁E ▁ ▁Robert ▁Wagner ▁ ▁( Rep ublic an ) ▁ ▁Maryland ▁General ▁Assembly ▁State ▁Senate , ▁District ▁ 3 4 A ▁State ▁Senator ▁Bob ▁Cass illy ▁( Rep ublic an ) ▁House ▁of ▁De leg ates , ▁District ▁ 3 4 A ▁ ▁Steve ▁Johnson ( D em ocrat ) ▁ ▁Mary ▁Ann ▁Lis anti ▁( D em ocrat ) ▁ ▁Cong r essional ▁De leg ation ▁US ▁Senate ▁ ▁Senator ▁Benjamin ▁L . ▁Card in ▁( D em ocrat ) ▁ ▁Senator ▁Chris ▁Van ▁Hol len ▁( D em ocrat ) ▁US ▁House ▁of ▁Representatives , ▁ 2 nd ▁Cong r essional ▁District ▁ ▁Congress man ▁C . A . ▁Dutch ▁Ru ppers berger ▁( D em ocrat ) ▁ ▁Aber de en ▁Pro ving ▁Gr ound ▁ ▁Aber de en ▁is ▁home ▁to ▁the ▁U . S . ▁Army ' s ▁Aber de en ▁Pro ving ▁Gr ound ▁( AP G ). ▁The ▁prov ing ▁ground ▁was ▁established ▁by ▁Act ▁of ▁Congress ▁and ▁came ▁into ▁operation ▁in ▁January ▁ 1 9 1 8 . ▁AP G ▁is ▁headquarters ▁of ▁the ▁United ▁States ▁Army ▁Test ▁and ▁E valu ation ▁Command ▁( ATE C ). ▁The ▁prov ing ▁ground ▁occup ies ▁more ▁than ▁ ▁in ▁Har ford ▁County . ▁More ▁than ▁ 7 , 5 0 0 ▁civ ili ans ▁and ▁ 5 , 0 0 0 ▁military ▁personnel ▁work ▁at ▁AP G . ▁ ▁Notable ▁people ▁William ▁Benjamin ▁Baker , ▁U . S . ▁Congress man ▁for ▁Maryland ' s