▁Congress ▁was ▁a ▁meeting ▁of ▁the ▁legisl ative ▁branch ▁of ▁the ▁United ▁States ▁federal ▁government , ▁consisting ▁of ▁the ▁United ▁States ▁Senate ▁and ▁the ▁United ▁States ▁House ▁of ▁Representatives . ▁It ▁met ▁in ▁Washington , ▁D . C . ▁from ▁March ▁ 4 , ▁ 1 8 4 5 , ▁to ▁March ▁ 4 , ▁ 1 8 4 7 , ▁during ▁the ▁first ▁two ▁years ▁of ▁James ▁Pol k ' s ▁presiden cy . ▁The ▁app ort ion ment ▁of ▁seats ▁in ▁the ▁House ▁of ▁Representatives ▁was ▁based ▁on ▁the ▁Six th ▁Census ▁of ▁the ▁United ▁States ▁in ▁ 1 8 4 0 . ▁Both ▁ch amb ers ▁had ▁a ▁Democratic ▁majority . ▁ ▁Major ▁events ▁▁ ▁March ▁ 4 , ▁ 1 8 4 5 : ▁James ▁K . ▁Pol k ▁became ▁President ▁of ▁the ▁United ▁States ▁ ▁October ▁ 1 0 , ▁ 1 8 4 5 : ▁The ▁Naval ▁School ▁( l ater ▁renamed ▁the ▁United ▁States ▁Naval ▁Academy ) ▁opened ▁in ▁Ann apolis , ▁Maryland ▁ ▁December ▁ 2 , ▁ 1 8 4 5 : ▁President ▁Pol k ▁announced ▁to ▁Congress ▁that ▁the ▁Mon roe ▁Do ctrine ▁should ▁be ▁strictly ▁enfor ced ▁and ▁that ▁the ▁United ▁States ▁should ▁ag gress ively ▁expand ▁into ▁the ▁West . ▁ ▁April ▁ 2 5 , ▁ 1 8 4 6 : ▁Open ▁conflict ▁over ▁border ▁disput es ▁of ▁Texas ' s ▁boundaries ▁began ▁the ▁Mexican – American ▁War ▁ ▁Major ▁legisl ation ▁▁ ▁May ▁ 1 3 , ▁ 1