The westernmost BL I-94 runs through the twin cities of Benton Harbor and St. Joseph along the former routing of US 12 and US 31/US 33 that now includes a section of the Lake Michigan Circle Tour in the state.

The loops in Kalamazoo, Battle Creek, Marshall, Albion, and Jackson were also formerly segments of US 12 which were later designated as separate version of Business US Highway 12 (Bus.

[10][11] When the business route was first constructed, it had half of a bridgeless diamond interchange each at Crystal and Euclid avenues, with the intent of building overpasses for both crossroads at a later date.

[20][21] The Great Lakes Circle Tours were approved by the Michigan Department of Transportation (MDOT) and its counterparts in Minnesota, Ontario, and Wisconsin.

[23] The interchange at the eastern terminus was rebuilt as part of the completion of the St. Joseph Valley Parkway (US 31 relocation); the reconstruction started in 2020.

BL I-94 runs concurrently along M-37 northwesterly from the freeway on the two-lane Columbia Avenue on the eastern edge of Fort Custer.

From there, the business loop follows West Dickman Road along a four-lane divided highway (except between 24th and 20th streets) through a residential area on the northern side of Battle Creek.

The center turn lane drops southeast of Wattles Road, and the business loop continues to its eastern terminus at exit 104 on I-94.

[36] In 1964, the western end of the business loop was realigned to follow Dickman Road west to Fort Custer and south along Skyline Drive to I-94.

[50][51] Then in 2008, BL I-94 was removed from the northern segment of I-194/M-66 freeway and rerouted to follow Dickman Road to Main Street back to Hamblin Avenue.

[52][53] To expand the blast radius for ammunitions testing at Fort Custer, MDOT rerouted the business loop and M-37 to run along the southern and eastern edges of the airport instead of following roads on the opposite sides.

At the interchange with M-96 about two miles (3.2 km) south, BL I-94 departs the fourl-lane freeway to follow Michigan Avenue northeasterly along a four-lane divided highway.

At the intersection with the two-lane Partello Road in Marengo Township, BL I-94 turns northerly off Michigan Avenue past several businesses to its eastern terminus at I-94's exit 112.

State maintenance starts at the end of those ramps to C Drive North and runs to Eaton Avenue where the business loop turns southward to cross the freeway.

East of downtown, BL I-94/M-99 passes through residential areas and turns northeasterly at the intersection with Clark Street, narrowing to two lanes.

The more rural section of Michigan Avenue carrying the business loop crosses into Parma Township in Jackson County.

At this time, Eaton Avenue was transferred to state control, and the rest of the former route of US 12 through Albion was redesignated Business US Highway 12 (Bus.

This interchange is also the eastern terminus of M-60 and the two run concurrently southward along a section of four-lane freeway west of Jackson County Airport.

On the western edge of downtown Jackson, traffic follows a one-way pairing of three-lane streets that form a loop around the center of the business district.

BL I-94 departs the loop north of the Grand River crossing near the Amtrak train station on the five-lane Michigan Avenue.

Ann Arbor Road turns eastward to run parallel to the south side of I-94 near Gilletts Lake.

US 12 was extended westward along Michigan Avenue to the new freeway west of town in Blackman Township and northerly to a new western terminus at I-94/US 12.

[80][81] The eastern end was updated further in 1968 to use Louis Glick Highway to connect to the northern half of the loop around downtown to Michigan Avenue.

[82][83] A set of connector streets on the western side of the downtown loop opened in November 1969 to streamline the flow of traffic further resulting in the last changes to the BL I-94 routing in Jackson.

The business loop passes to the north of University of Michigan's Central Campus and then turns southward through it on the five-lane Washtenaw Avenue.

The business loop follows the four-lane freeway southward through a residential area on the edge of Ann Arbor and ends at exit 180 on I-94.

[96] BL I-94 was rerouted on the east end to follow the new US 23 freeway, returning the Carpenter Road alignment to local control.

On the eastern side of the city, the business loop turns northward along the four-lane divided Gratiot Boulevard near the St. Clair River.

North of Ravenswood Road, BL I-94 splits into the one-way pairing of two-lane Military Street (northbound) and Electric Avenue (southbound).

North of the freeway crossing, the business loop intersects the southern end of M-25 and turns westward onto Hancock Street for two blocks.