In the United States, all bills originating in the House of Representatives begin with "H.R." and all bills originating from the Senate begin with an "S.". Every two years, at the start of odd-numbered years, the United States Congress recommences numbering from 1, though for bills the House has an order reserving the first 20 bill numbers and the Senate has similar measures for the first 10 bills. Joint resolutions also have the same effect as bills, and are titled as "H. J. Res." or "S. J. Res." depending on whether they originated in the House or Senate, respectively. This means that two different bills can have the same number. Each two-year span is called a "congress", tracking the terms of Representatives elected in the nationwide biennial House of Representatives elections, and each congress is divided into year-long periods called "sessions".