Business Loop I-75 - Troy

The 8.9 mile route of Business Loop I-75 followed old U.S. 25 between Exits 69 and 78. County Road 25A, named because U.S. 25 was still posted in Miami County at the time, stems north from I-75 along former U.S. 25 through suburban areas north of Tipp City to Market Street in south Troy. CR 25A transitions into Market Street northwest to SR 55, which follows the street northeast to Downtown.

A traffic circle joins SR 55 (Market Street) with SR 41 (Main Street) in the Troy business district. There Business Loop I-75 turned west and overlapped with SR 41 on Main Street to Elm Street north. Beyond the city line, County Road 25A resumes as the name of old U.S. 25 as it parallels the Great Miami River north to I-75.

Harrison Page noted at least a dozen shields for Business Loop I-75 in the early 2000s. Of these, only three were posted outside the Troy city limits and none at the traffic circle between Main and Market Streets Downtown. The route is also unmarked on guide signs for the respective County Road 25A exits.