John Wesley Powell, who was the first to define the extent of the family, noted that its boundaries were the Pacific Ocean to the west, Wintuan territory in the Sacramento Valley to the east, the head of the Russian River to the north, and Bodega Head and present-day Santa Rosa to the south (Powell 1891:87-88).

Only Northeastern Pomo was not contiguous with the other Pomoan languages, being separated by an intervening region of Wintuan speakers.

This naming convention quickly gained wide acceptance and is still in general use, except for the substitution of "Kashaya" for Barrett's "Southwestern Pomo".

Essentially identical versions of this classifications are presented in Oswalt and McLendon's "Introduction" to the Pomo chapters in Heizer, ed.

The most important dissenter was Abraham M. Halpern, one of the few linguists since Barrett's time to collect comparative data on all of the Pomoan languages.