It begins at an intersection with NY 98 in the town of Freedom and proceeds southeastward across mostly rural areas of Cattaraugus and Allegany counties to Rushford Lake.

Not far from the latter junction, the creek empties into Rushford Lake, a small water body located on the Rushford–Caneadea town line.

NY 243 loosely parallels the northern edge of the lake, serving several local roads that lead south to lakeside houses comprising the hamlet of Balcom Beach.

Past the lake, the roadway heads eastward across an undeveloped part of the town of Caneadea, veering to the north and south as it runs along the base of several hills.

[5][6] In the 1930 renumbering of state highways in New York, hundreds of state-owned roads were given posted route numbers for the first time.