NY 33A was assigned as part of the 1930 renumbering of state highways in New York, but only from Riga to Rochester.

Less than a quarter of a mile (0.4 km) from its western terminus, NY 33A meets Interstate 490 (I-490) at exit 2.

[3] Now in the town of Riga, NY 33A becomes Chili–Riga Center Road as it traverses a largely rural portion of southwestern Monroe County.

East of Riga hamlet, NY 33A heads generally northeastward, passing by Black Creek Park as it enters the town of Chili.

Past Chili Center, NY 33A heads northeast through a residential neighborhood and into the town of Gates.

[3] East of Brooks Avenue, NY 33A passes through a small residential area before entering a more industrial neighborhood surrounding the Erie Canal and the Rochester city line.

The surroundings become significantly more residential east of the railroad as the route heads northeastward toward downtown Rochester.

From there, the route continued for an additional 1 mile (1.6 km) to the original city limits, where it ended near the intersection of Chili Avenue and Post Street.

[10] Within two years, a highway extending from Batavia to Rochester by way of Bergen and Gates was designated as NY 33.