United States Olympic Trials (track and field) fill out the field. Since 1972 there have been a minimum of 24 entries in any event, with the popular sprint events 100 meters, 200 meters, 400 meters and 110 meter hurdles having a minimum of 32 entries. Since 1992, athletes achieving the "A" standard are funded to attend the Olympic Trials, while "B" standard athletes have to pay their own way to the meet. Unlike many other countries, who have a selection committee, the selection to the United States Olympic Team is exclusively by results on the track. It's "do or die" in the prescribed event. If two or
Running an indoor world championship event. Other less-common events include the 50 metres, 55 metres, 300 metres and 500 metres which are used in some high and collegiate competitions in the United States. The 150 metres, is rarely competed: Pietro Mennea set a world best in 1983, Olympic champions Michael Johnson and Donovan Bailey went head-to-head over the distance in 1997, and Usain Bolt improved Mennea's record in 2009. Middle distance running events are track races longer than sprints up to 3000 metres. The standard middle distances are the 800 metres, 1500 metres and mile run, although the 3000 metres may