Cropsey was born on his father Jacob Rezeau Cropseys farm in Rossville on Staten Island, New York, the oldest of eight children. As a young boy, Cropsey had recurring periods of poor health. While absent from school, Cropsey taught himself to draw. His early drawings included architectural sketches and landscapes drawn on notepads and in the margins of his schoolbooks.
Trained as an architect, he set up his own office in 1843. Cropsey studied watercolor and life drawing at the National Academy of Design under the instruction of Edward Maury and first exhibited there in 1844. A year later he was elected an associate member and turned exclusively to landscape painting; shortly after he was featured in an exhibition entitled "Italian Compositions".