The FBI History Site

FBI Seal, A Short History of the FBI, Famous Cases, Five Historical Firearms.  The Bureay was created in 1908, and was called the "Bureau of Investigation;" it  became the United States Bureau of Investigation on July 1, 1932 and the FBI in 1935.  Read about the history, when fingerprint collecting started, when the National Motor Vehicle theft act was passed, and other important period references.

The destination of plenty of criminals (and not a few innocents) in the Roaring 20s.  If you are running a campaign, you may want to check out what captial punishment your state(s) allowed for. Hanging and more esoteric methods were still quite common. This will tell you all (perhaps more) than you wanted to know about a most grisly method of "humane" execution.

Life as a San Francisco Beat Cop

An excellent source on the penultimate gangster weapon, explaining how gangsters got them, how much they cost, etc. 
 

FBI FOIA Files 

Mostly from the 30's, These famous cases include the St. Valentine's Day Massacre in 1929.  Also Bonnie and Clyde,  John Dillinger, Baby Face Nelson

A good general description of Capone's career, from the FBI.  Capone was run in partially by agents of the Bureau of Investigation, the FBI's precursor.

Minor notes on Al Capone's Driver.

A private site that is no longer being maintained, but remains up. Al Capone and others. 

From the Newcastle Brown Ale Site - a Capsule of Al Capone

Adventure.Com Encyclopedia entry for Al Capone

KTEH San Jose Public Televeision Presents this show. Dillinger, Luciano, Capone, and others. Note Crippen for "Gilded age" reference.

Second Season - Mafia and the KKK

Cheesy museum in Niagra Falls. Fun, and has information on several 20s crime figures

Jazz Musician Milt Hinton remembers Al Capone

Two immigrant anarchists convicted of murder - one of the most controversial cases of the 1920s.

The Great sports scandal of the 20s - how the 1919 World Series was bought.

Addison and Wilson Mizner, real life models for Stephen Sondheim's "Wise Guys".  This details dealings in Florida in the early 20s before they went to California and opened the "Brown Derby" restaurant. 
 
 

Temperance and Prohibition 

Ohio State University Pages - Scans from "The Ram's Horn" and links to other historic prohibition sites.

Same as above, a direct link to the 1920s period

Retro Magazine article, mentions Texas Guinan, Edward VIII and "The Real McCoy"

"PRO" Statement on Prohibition (from the University of Ohio site)

"PRO" Statement on Prohibition (from the University of Ohio site)

"CON" Statement on Prohibition (from the University of Ohio site)

"CON" Statement on Prohibition (from the University of Ohio site)

Digital archive of the Anti-Saloon League 1893-1933, one of the moving forces behind prohibition.  Posters, text, etc.  The League left a legacy of printed material at a site bequeathed to the Westerville Ohio Public Library which houses the Anti-Saloon League Museum.