It would certainly need 'Iowa' in the _con csv, but if there's no other IA US20His files then city name or abbrev strike me as unneccessary. I'd go with Waterloo if an actual city is desired as it's the biggest.
stuff like the main cross-state route of US66His being US66HisChi in IL, US66HisStL in MO and US66HisOkl in OK is mostly due to every other bannered route in the US having (and I remember Tim being really adamant that the abbrev and city fields be used on the few bannered UK routes, even when there was only route with that number+banner combo and I suggested getting rid of a lot of them) abbrevs and cities in .csvs even if its a unique route and so it's mostly force of habit / conformity to existing standards rather than something I want to impose.
I know it's not an active system, but we have the following points in use on the routes that are replaced. I suggest adding the old route names as AltRouteNames just to preserve these travels, even if it gets updated out before too long.
ia.us020hiscor(6): CRL51 IA31
ia.us020hisfor(41): CHR75 CRN57 IA471_N
ia.us020hisiow(14): CRC65_E CRD15/D20
ia.us020hiswat(27): IA14 WATLIM
ia.us020hisjes(5): CRD20 CRV71
ia.us020hisman(17): CRW40 US20_E
ia.us020hisepw(11): US20_E US20_W
ia.us020hisdub(4): 4THST GRAAVE
