[1] Acer hillsi is known from a single specimen which was recovered from the Burke Museum of Natural History and Culture location UWBM A0307, an outcrop of the early Eocene, Ypresian[2] Klondike Mountain Formation in Republic, Washington.

[2] The plant community preserved in the Klondike Mountain formation is a mixed conifer–broadleaf forest with large pollen elements of birch and golden larch, but also having notable traces of fir, spruce, cypress, and palm.

[1] The species was described from a solitary type specimen, the holotype samara, number UWBM 56260 A, B, which is currently preserved in the paleobotanical collections housed at the Burke Museum, part of the University of Washington in Seattle.

[1] The specimen was studied by paleobotanists Jack A. Wolfe of the United States Geological Survey, Denver office and Toshimasa Tanai of Hokkaido University.

[1] The etymology of the chosen specific name hillsi is in recognition L. V. Hills who allowed Wolf and Tanai access to his extensive fossil collection and for his contributions to paleobotany and palynology.