Every four years that a President must be elected. so 2008, 2004, 2000, 1996, 1992, 1988 etc.
May of odd number of years.
The two major parties hold national conventions every four years, primarily for the purpose of nominating a candidate for President.
republicans
How many were ratified by conventions held in the states?
Democrats controlled BOTH house from 1955 until 1980 (26 years). From 1981 until 1987 the Republicans controlled the Senate and the Democrats the House. Democrats recaptured both houses in 87 and held them until 95 when the Republicans took both houses and held them until 2005.
delegates from each state select political parties'nominees for president
any big city
Nominating conventions are still held but have been obsolete for many years as those decisions are made in the primaries.
They decide on party platforms and nominate presidential/vice-presidential candidates.
Aug. 12
primary elections and caucuses are held
43 years, 299 days is the Republicans longest life expectancy in terms of years.