Here's a little bit of information regarding the United States during the war and afterwards, since we haven't touched on it much.
United States elections from 1916 to 1926
1916:
Presidential: Woodrow Wilson (D-VA) beats Charles E. Hughes (R-NY)
House of Representatives: Republicans gain 19 seats; Democratic-Socialist-Progressive Coalition maintains narrow majority
R: 216, D: 214, P: 3, S: 1
Senate: Republicans gain 2 seats,Democrats lose 2 seats
R: 42, D: 54
1918:
House of Representatives: Republicans gain 33 seats, take majority
R: 249, D: 183
Senate: Republicans gain 5 seats, Democrats lose 5 seats
R: 47, D: 47
1920:
Presidential: Leonard Wood (R-NH) beats James M. Cox (D-OH)
House of Representatives: Republicans gain 62 seats
R: 311, D: 121
Senate: Republicans gain 10 seats
R: 57, D: 37
1922:
House of Representatives: Democrats gain 76 seats
R: 235, D: 197
Senate: Democrats gain 6 seats
R: 51, D: 43
1924:
Presidential: John W. Davis (D-WV) beats Leonard Wood (R-NH)
House of Representatives: Democrats gain 28 seats, take majority
R: 207, D: 225
Senate: Democrats gain 6 seats, take majority
R: 45, D: 49
1926:
House of Representatives: Republicans gain 3 seats, Socialists gain 3 seats.
R: 199, D: 230, S: 3 seats
Senate: Republicans gain 1 seats, tie with Democrats -- Socialists gain 2 seats.
R: 46, D: 46, S: 2