The 100th United States Congress began on January 3, 1987. There were 12 new senators (ten Democrats, two Republicans) and 50 new representatives (27 Democrats, 23 Republicans) at the start of the first session. Additionally, one senator (a Republican) and eight representatives (five Democrats, three Republicans) took office on various dates in order to fill vacancies during the 100th Congress before it ended on January 3, 1989.