You'll find that most long haul trailers are registered in places like that. The reason is simple . Buy once cry once. I used yo register mine in Maine . You could buy up to a 20 year registration and be left alone by the taxaholic places like VT ,NY NJ on an annual basis. Too bad Maine got greedy a few years back so there's no savings anymore. The vast majority of all the big rigs trailers I've seen over the decades use those Indiana tags . It just makes financial sense and theres nothing the high priced states can do about it.
Washington county, Ohio is code 84. Ohio has 88 counties and the number goes in alphabetical order. Ohio went back to the county name on the plate in 2018.
NEWS Flash : Ohio no longer issues or requires a front licence plate on most vehicles as of July 1st, 2020.
Ohio offers a 5 year registration sticker for personal vehicles or anything between 1-5 years as desired. Few people choose more than one year.