Sloane eventually returned to New York City and settled in the Merryall area of New Milford, Connecticut, where he began painting rustic landscapes in the tradition of the Hudson River School.

In the 1950s, he began spending part of the year in Taos, New Mexico, where he painted western landscapes and particularly luminous depictions of the desert sky.

He wrote and illustrated scores of books on Colonial-era tools, architecture, farming techniques, folklore, and rural wisdom.

A young woman who was a passer-by saw Sloane go into cardiac arrest as he held onto a parking meter before collapsing to the sidewalk; she telephoned for help from a nearby phone booth.

His most famous painted work is probably the skyscape mural, Earth Flight Environment, which is still on display in the Independence Avenue Lobby in the Smithsonian's Air and Space Museum.