Video: 'Iowa Caucus History: George McGovern’s Early Momentum in 1972'

(Monday, January 24, 1972, caucuses scheduled to convene at 8:00 p.m. CST; during the 1972 Democratic Party presidential primaries) — The Iowa Caucuses, which would mark the opening of delegate selection in U.S. presidential election campaigns, was conducted for the first time tonight by the Democratic Party (Republicans would hold their first Iowa caucuses in 1976).

Video: 'How the Iowa caucuses shape history'

Unlike primary elections in most other U.S. states, where registered voters go to polling places to cast ballots, Iowans instead gather at local caucus meetings to discuss and vote on the candidates.

In the first Democratic Iowa Caucus on this day, a long-shot candidate, U.S. George McGovern, placed second behind national front-runner U.S. Senator Edmund Muskie. However, more votes went to “uncommitted” than to any particular candidate.