Hilldale is most likely just a compound word combining “hill” and “dale”, referring to this street’s descent from the foothills to the flats, but there’s a chance that it’s also a cute reference to Hilda Horowitz (née Topper, 1889-1975), wife of local shopkeeper/developer Al Horowitz (see Phyllis Avenue). Regardless, the upper portions of Hilldale were born with other names: Conklin Street (north of Sunset) and Whipple Avenue (between Sunset and Cynthia). Conklin and Whipple were both named by 1907, before the lower part of Hilldale even existed. (Conklin was for realtor Leon R. Conklin; Whipple was likely for H.W. Whipple, who bought some land from William and Mary Larrabee in 1898.) Lower Hilldale was laid out and named sometime between 1910 and 1915; I don’t know when it absorbed Conklin and Whipple.
Find it on the map:
