It is most commonly used to carry traffic from Buffalo to the village of East Aurora, where Fisher-Price and Moog, Inc are headquartered.

After passing by Emery County Park, NY 16 leaves the expressway back onto Olean Road on one of three junctions that only allow access in one cardinal direction, this one to the south as a northbound exit and southbound entrance.

North of here, entering the town of Elma, it turns to the west to meet with Maple Street at the final single-direction junction, a northbound entrance and southbound exit.

The expressway then turns northwest to intersect with Jamison Road (formerly NY 422) by way of a full diamond interchange.

NY 400 also passes a small industrial area containing manufacturing plants for Moog, Inc, Motorola, Servotronics, and Steuben Foods located on Maple Street and Jamison Road.

After a final exit for NY 16, it encounters the New York State Thruway (I-90) at the beginning of I-90's eight-lane section through Buffalo, signifying its high use during rush hour.