Records 1912–1976 (+) plus sign denotes en route time during longer race "y" denotes time for
440 yards, ratified as a record for this event "A" indicates that the time was set at altitude. The "Time" column indicates the ratified mark; the "Auto" column indicates a fully automatic time that was also recorded in the event when hand-timed marks were used for official records, or which was the basis for the official mark, rounded to the 10th of a second, depending on the rules then in place.
Records post-1976 From 1975, the IAAF accepted separate automatically electronically timed records for events up to 400 metres. Starting January 1, 1977, the IAAF required
fully automatic timing to the hundredth of a second for these events. Lee Evans' 1968 Olympic gold medal victory time of 43.86 was the fastest recorded result to that time. For the period when the record automatic time was Lee Evans' mark of 43.86, the progression excluding races run at high altitude (above 1,000 metres) was as follows: ==Notes==