Vehicle registration plates of Iowa
Type Design Serial format Notes
Apportioned Power Unit Green on white P B 1234 S B 1234 Issued to trucks and tractor units
Apportioned Trailer Green on white R B 1234 T B 1234 Issued to semi-trailers
County Sheriff 's Department Green on white with Sheriff 's star-shaped seal at left S 00 -1234 Uses the numeric county-code system that was used on standard passenger plates until 1979 ( so , for instance , a plate whose serial starts with S77 would indicate a deputy from Polk County ) . The numbers to the right of the hyphen correspond to the deputy 's badge number . These plates are used only on marked units
Dealer Black on white with blue state name D 1 D 12 D 123 D 1234 Plus three-digit suffix that ascends for each dealer
Motorcycle Similar to standard passenger base 1234 AB AB 1234
Official Black on white 123456
Official County Black on white 12345
Special As standard passenger base , but with vertical SPECIAL at left 123 S BC ( 000 SAA to 999 SHG )
State Patrol Black on yellow with two red stars either side of serial 12 123 The serial number corresponds to the badge number for that state trooper , excluding post 16 , who drive pool cars assigned numbers which are currently not being used by another trooper . These plates are used only on marked units ; unmarked units use regular state-issued plates
Trailer As standard passenger base 1234 AB AB 1234
Current non-passenger and optional plates -- Non-passenger plates
The U.S. state of Iowa first required its residents to register their motor vehicles in 1904. Registrants provided their own license plates for display until 1911, when the state began to issue plates.