NY 324 once extended northwest to downtown Niagara Falls; however, it was truncated to its current western terminus on January 1, 1962.

[5] Maintenance of the route is split between NYSDOT, the New York State Thruway Authority (NYSTA), and Erie County.

[6][7] From I-190 exit 20, NY 324 runs in a more southeasterly direction, serving as the main commercial strip on Grand Island, before it overlaps I-190 in order to cross the Niagara River.

The eastbound route of NY 324 is unable to do so; instead, it parts company with the Interstate Highway on the other side of the river at exit 15, where it turns north to parallel I-190 on Kenmore Avenue.

After 250 yards (229 m), it veers east onto the Town of Tonawanda's portion of Grand Island Boulevard for 0.5 miles (0.8 km) to a junction with Sheridan Drive.

Past the Youngmann development abates, green returns to the roadside and the median ends, although the road remains four-lane and high-volume.

After Harris Hill Road, the highway bends to the southeast once again for a final mile into its eastern end at Main Street (NY 5).

[5] Sheridan Drive was constructed during the early 1920s as a town of Tonawanda project to help alleviate the anticipated growth of the village of Kenmore.

[11] To make things worse, the new road did not bring the immediate influx of business that was advertised and was looking early on as a giant mistake on the part of the county and towns.

[14][15] The route was extended one final time by 1948 to follow NY 384 westward from the North Grand Island Bridge into downtown Niagara Falls.