In U.S. politics, general elections are elections held at any level (e.g. city, county, congressional district, state) that typically involve competition between at least two parties. General elections occur every 4 years (depending on the positions being filled with most positions good for four years) and include the presidential election, but unlike parliamentary systems the term can also refer to special elections that fill out positions prematurely vacated by the previous office holder (e.g. through death, resignation, etc.). Some parallels can be drawn between the general election in parliamentary systems and the biennial elections determining all House seats, although there is no analogue to "calling early elections" in the U.S., and the members of the elected U.S. Senate face elections of only one-third at a time at two-year intervals including during a general election.