▁Indian apolis ▁ 5 0 0 ▁while ▁maintain ing ▁a ▁full - time ▁schedule ▁in ▁Formula ▁One . ▁This ▁would ▁require ▁them ▁to ▁travel ▁between ▁Indian apolis ▁and ▁Europe ▁during ▁the ▁month ▁of ▁May , ▁usually ▁between ▁Ind y ▁and ▁the ▁Mon aco ▁Grand ▁Prix ▁at ▁Monte ▁Carlo , ▁two ▁of ▁the ▁three ▁components ▁of ▁the ▁Tri ple ▁Crown ▁of ▁Mot ors port . ▁For ▁many ▁years , ▁Ind y ▁and ▁Mon aco ▁were ▁not ▁held ▁on ▁the ▁same ▁day . ▁Furthermore , ▁prior ▁to ▁ 1 9 7 1 , ▁the ▁Ind y ▁ 5 0 0 ▁was ▁held ▁on ▁May ▁ 3 0 ▁regardless ▁of ▁the ▁day ▁of ▁the ▁week ▁( unless ▁it ▁fell ▁on ▁a ▁Sunday , ▁in ▁which ▁case ▁it ▁was ▁scheduled ▁for ▁Monday ▁May ▁ 3 1 ). ▁With ▁the ▁Ind y ▁ 5 0 0 ▁often ▁falling ▁on ▁a ▁week day , ▁and ▁Mon aco ▁usually ▁held ▁on ▁a ▁Sunday ▁a ▁week ▁or ▁two ▁prior , ▁travel ▁bur dens ▁were ▁relatively ▁work able . ▁ ▁Racing ▁at ▁both ▁Ind y ▁and ▁Mon aco ▁in ▁the ▁same ▁year ▁became ▁mostly ▁impossible ▁after ▁Ind y ▁was ▁moved ▁to ▁race ▁on ▁Sunday ▁starting ▁in ▁ 1 9 7 4 , ▁and ▁Mon aco ▁like wise ▁was ▁eventually ▁moved ▁to ▁the ▁last ▁Sunday ▁in ▁May ▁( same ▁day ▁as ▁Ind y ), ▁ending ▁just ▁a ▁couple ▁hours ▁before ▁the ▁green ▁flag ▁dropped ▁at ▁Indian apolis . ▁ ▁Same ▁week end ▁races ▁There ▁are ▁other ▁less er , ▁inform al ▁uses ▁of