The route was originally an at-grade highway for its entire length, following what is now East Washington Avenue (CR 35), Middletown Road (CR 33) from Pearl River, and Main Street to West Nyack Road (then NY 59) in Nanuet. Here, NY 304 turned east, overlapping with NY 59 to access its current alignment.
The route was initially a straight road for its entire length, following what is now East Washington Avenue (CR 35), Middletown Road (CR 33) from Pearl River, and Main Street to West Nyack Road (then NY 59) in Nanuet.  NY 304 then shifted east, merging with NY 59 to reach its current path.