Just west of US Highway 127 (US 127), the street transitions into a six-lane boulevard and proceeds easterly to the East Lansing city limit.

[6] No section of M-143 is listed on the National Highway System,[7] a network of roads important to the country's economy, defense, and mobility.

[2][3] As part of the creation of the Capitol Loop, M-143 and Michigan Avenue in Lansing was partially transferred back to local control.

The section between Cedar and Larch streets was retained as part of the new Capitol Loop and the remainder inside the city of Lansing was removed from the state trunkline highway system on October 13, 1989.

[13] Since then, MDOT has used the trunkline's designation on maps and in brochures related to a 2013 reconstruction project on Michigan Avenue in East Lansing.