Sources Exhausted

National Sources:

• Congressional Pictorial Directory
• "Autobiographies and portraits of the President, cabinet, Supreme court, and Fifty-fifth Congress"
• "The United States Red Book" (54th congress)
• "Public men of to-day; being biographies of the President and Vice-president of the United States, each member of the Cabinet, the United States senators and the members of the House of representatives of the Forty-seventh Congress, the chief justice and the justices of the Supreme court of the United States, and of the governors of the several states" (47th Congress)
• "McClees' gallery of photographic portraits of the senators, representatives & delegates of the thirty-fifth Congress." -- photo of Caruthers missing online, get paper copy?
• "Who's Who in the Pacific Southwest"

State Registers / Blue Books / Statewide resources (these are generally useful for 1900+ around when photos became routine in them):

• Alabama Official and Statistical Register
• Arkansas Historical Report of the Secretary of State
• Connecticut State Register
• Georgia Official Register
• Illinois Blue Book
• Biographical dictionary and portrait gallery of the representative men of the United States (Illinois)
• Iowa Red Book
• Massachusetts Manual for the General Court
• Michigan Blue Book
• Minnesota Blue Book (Legislative Manual)
• Missouri Blue Book
• New York Red Book
• North Carolina manual
• Pennsylvania State Legislature and State Senate
• Nebraska Blue Book
• Representing Texas book
• West Virginia Blue Book
• Wisconsin Blue Book
• "The Columbian biographical dictionary and portrait gallery of the representative men of the United States : Wisconsin volume"

Not exhausted:

• Pennsylvania Manual (mostly under copyright, somehow?)

Completed States:

• Alaska
• Arizona
• Hawaii
• Idaho
• Montana
• New Mexico
• North Dakota
• Oklahoma
• South Dakota
• Utah
• Washington
• Wyoming