Interestingly, I had just found the Cheyenne cite ("emigrants in wagon tents") in 1880 Census a day earlier, on 10/6, as well as (finally!) a cite for Leander and Sarah Bemis (his second wife) in 1900 ... at Monticello Precinct, Cowlitz County.
The 1880 enumeration includes another mystery, however. This is whether the Elizabeth Bemis shown as a daughter actually was (1) a daughter of Leander from first marriage (I don't think so); (2) a daughter of Sarah from a prior marriage (possibly, because 1900 Census says she'd had four children); or (3) the wife (or widow) of one of Leander's sons (possibly of James).
The 1900 enumeration at Monticello Precinct suggests the possibility that this same Elizabeth later married an Asberry (James A.?) Brewer. This is because their family cluster includes a stepdaughter, Clara Bemis.
Also, Cowlitz County, Washington Marriage Records for 1854 - 1900 show this: "BREWER, James A mar 8 Jan 1882 at res of Mrs Elizabeth J Beamis to Elizabeth J BEAMIS by J V Huntington w J W Brewer and John Cummins."
It is instructive, perhaps, that Henrietta Brewer (a sister of James A.) was married to Frederick L. Bemis (a son of Leander). Like Leander Bemis and the Brewer family, Fred and Henrietta also were living in Monticello Precinct in 1900.