▁a . m ., ▁an ▁aer ial ▁bomb ▁is ▁set ▁off ▁to ▁signal ▁the ▁opening ▁of ▁the ▁gates . ▁ ▁At ▁ 8 ▁a . m ., ▁the ▁" Par ade ▁of ▁B ands " ▁march es ▁a ▁lap ▁around ▁the ▁racing ▁circuit . ▁N umer ous ▁march ing ▁bands ▁from ▁nearby ▁and ▁neighbor ing ▁high ▁schools ▁and ▁univers ities ▁entertain ▁the ▁early ▁arriv ing ▁fans . ▁This ▁tradition ▁dates ▁back ▁to ▁ 1 9 2 2 , ▁and ▁celebrated ▁its ▁ 9 0 th ▁anni versary ▁in ▁ 2 0 1 5 . ▁Most ▁of ▁the ▁bands ▁in ▁attend ance ▁also ▁particip ate ▁in ▁the ▁ 5 0 0 ▁Festival ▁Par ade ▁dow nt own ▁the ▁day ▁before . ▁Trad itional ▁participants ▁include ▁the ▁Pur due ▁All - American ▁March ing ▁Band ▁( al ong ▁with ▁the ▁World ' s ▁L arg est ▁Dr um ▁which ▁is ▁driven ▁around ▁the ▁track ) ▁and ▁Speed way ▁High ▁School . ▁Due ▁to ▁rain ▁show ers ▁the ▁morning ▁of ▁the ▁race ▁in ▁ 2 0 0 7 , ▁the ▁bands ▁instead ▁par aded ▁around ▁the ▁in field , ▁including ▁parts ▁of ▁the ▁in field ▁road ▁course , ▁as ▁track ▁cre ws ▁were ▁working ▁to ▁dry ▁the ▁track ▁with ▁tr uck s ▁and ▁jet ▁dry ers . ▁ ▁The ▁Pur due ▁University ▁All - American ▁March ing ▁Band ▁plays ▁several ▁pre - race ▁songs , ▁including ▁" On ▁the ▁B anks ▁of ▁the ▁W ab ash " ▁and ▁" St ars ▁and ▁St ri pes ▁Fore