As well as the alphabetical name listing, most city directories have a business section classified by occupation, grocers, physicians, etc.
Where available it is often easier to browse the paper copies. In HOLLIS+ search: Cambridge directories, adjusting 'Limit to:any field' to 'Limit to: subject'.
The major online sources are:
Ancestry Library Edition includes many city directories. Open Search in top black band, and choose Card Catalog. Then choose Schools, Directories & Church Histories, then City & Area Directories. Then refine by geography and/or date. There are UK as well as American directories... Many of the directories can be browsed (on the right). For example; U.S. City Directories, 1822-1995
HathiTrust In Advanced Catalog search try:
- Title: Boston [etc.] – Subject: Directories
- Also try Title: Boston Directory
These produce overlapping but different results.
Some directories are available only on microfiche or microfilm:
American directories through 1860. 6820 microfiches
Guide: Bibliography of American directories through 1860, by Dorothea N. Spear. Worcester, Mass., American Antiquarian Society, 1961, 389 p.
City directories of the United States. Harvard only has these directories for Boston (1861-1960), Cambridge (1902-1935) and Columbus, Ohio (1861-1901), all of which are available online.
For cities we don’t have use U.S. City Directories on Microfilm in the [Library of Congress] Microform Reading Room (bottom of page) to specify the reel, then Interlibrary Loan.
This book offers an appendix on the biases and limitations of city directories:
The plain people of Boston, 1830-1860: a study in city growth, by Peter R. Knights. NY: Oxford University Press, 1971, 204 p.
Historical Directories of England & Wales (1760s-1910s)
Overview of British directories: Directories in England and Wales. For other countries, change the country name in the url.