Could this be your Mary J. (Allen) Izar?
1880 U.S. Census [June 8]
E.D. 10, Page 20
District 10, Denver, Arapahoe, Colorado
William H. Izor Age 30 b.Indiana
Mary J. Izor Age 31 b.Ohio father:Virginia mother:Ohio
Atha Izor Age 3 b.Iowa
Source Citation: Year: 1880; Census Place: Denver, Arapahoe, Colorado; Roll: T9_88; Family History Film: 1254088; Page: 215.4000; Enumeration District: 10; Image: 0252.