9 7 . ▁ ▁Un like ▁ 1 : 2 4 ▁scale ▁tracks , ▁HO ▁race ▁tracks ▁can ▁be ▁small ▁enough ▁to ▁fit ▁in ▁common ▁bas ements . ▁Therefore , ▁most ▁state ▁organizations ▁run ▁some , ▁if ▁not ▁most , ▁of ▁their ▁series ▁on ▁home ▁tracks ▁as ▁opposed ▁to ▁h ob by ▁shop ▁tracks . ▁Additionally , ▁home ▁tracks ▁are ▁often ▁used ▁for ▁national ▁competition . ▁ ▁HO ▁Sc ale ▁O val ▁racing ▁is ▁very ▁popular ▁in ▁the ▁N ort he astern ▁United ▁States . ▁The ▁cars ▁are ▁m old ed ▁to ▁look ▁like ▁D irt ▁Mod ified s ▁and ▁S print ▁C ars . ▁The ▁S print ▁C ars ▁and ▁D irt ▁Mod ified ▁cars ▁are ▁rac ed ▁on ▁o val ▁tracks ▁anywhere ▁from ▁ 8 ▁lan es ▁to ▁ 4 ▁lan es . ▁ ▁USA ▁competition ▁classes ▁▁ 1 : 2 4 ▁racing ▁classes ▁Most ▁ 1 : 2 4 ▁racing ▁series ▁use ▁some ▁variation ▁of ▁the ▁US RA ▁Division ▁ 1 ▁or ▁Division ▁ 2 ▁rules . ▁The ▁US RA ▁rules ▁have ▁their ▁roots ▁in ▁the ▁N CC ▁rules ▁of ▁the ▁early ▁ 1 9 7 0 s ▁which ▁were ▁written ▁with ▁the ▁goal ▁of ▁making ▁a ▁number ▁of ▁under - classes ▁in ▁slot ▁racing ▁to ▁allow ▁more ▁divers ity ▁in ▁competition . ▁ ▁US RA ▁division ▁ 1 ▁a ) ▁Spec - 1 5 : ▁Am ateur ▁only ▁b ) ▁GP - 1 2 : ▁Am ateur ▁and ▁Ex pert ▁c ) ▁International ▁ 1 5 ▁( 1 5