Here's what you should know if it rains at the Indy 500 on Sunday:

Rain-shortened races can be official

Drivers must complete 101 laps before a race is considered official.

In 1976, pole-sitter Johnny Rutherford earned his second-career Indy 500 victory, taking the lead in lap 80 and maintaining the top spot when the race was postponed and eventually called 102 laps in. His 255 completed miles make that the shortest official recorded race.

There have been six other rain-shortened races, according to indianapolismotorspeedway.com: 1926, 1950, 1973, 1975, 2004 and 2007.

Complete postponement

If the race is postponed by rain Sunday, it will be completed Monday. The start time will depend on several factors, including the forecast.

The 500 has had three complete postponements in its history. The most recent was in 1997, when the race was scheduled for Sunday, May 25, and postponed by rain until Monday, only to be postponed again after just 15 laps. The race was completed Tuesday.

The 1986 race was scheduled for Sunday, May 25. Rain postponed the race until Saturday, May 31. In 1915, the race was scheduled on Saturday and was postponed. With Memorial Day landing on Sunday, organizers decided to reschedule the race for Monday.

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Partial postponements

If fewer than 101 laps are run, the race will pick up the next dry day.

In 1973, the race was scheduled for Monday, May 28, but there was a first-lap accident and it could not be re-started due to rain. It was postponed again the next day but on May 30, the field ran 332.5 miles and it was ruled complete.

In 1967, the race was postponed after 18 laps and finished the following day.

How quickly the track can be dried

IMS has used a sealant on the track the past few years that speeds up drying of the track. How long it takes to dry is dependent on the amount of rain, however. After heavy rain during qualifying in 2019, it took about 90 minutes to dry the track.

Save your tickets

If the race is postponed re-entry is allowed, said IMS Senior Director of Communications Alex Damron. Use the same ticket to receive entry.

Follow IndyStar sports producer Akeem Glaspie on Twitter at @THEAkeemGlaspie.

This article originally appeared on Indianapolis Star: Indy 500 weather delay: Does the Indy 500 run in the rain?