Midwestern city directories online

Several Midwestern cities have digital images of their pages scanned for free online access, where you can search by family name:

Chicago, IL 1844
Cleveland, OH 1837
Ohio City, OH 1837
Monroe, WI 1891

Entries include surname, residents of the household, occupations of occupants, and a citation for an address. The most obvious advantage for using city directories is that fact that you can pinpoint family members between federal and state censuses.
See for yourself at: olddirectorysearch.com

Happy hunting!