Thomas Joseph O'Brien (April 30, 1878 – April 14, 1964) of Chicago was a U.S. Representative from Illinois, 1933–39, 1943–64, and as Cook County Sheriff from 1938 through 1942.

[2] He became the "Dean" of Chicago delegates and played a role in the early career of Dan Rostenkowski.

[3] O'Brien died in office of a stroke on April 14, 1964, and was buried at Queen of Heaven Cemetery in Hillside, Illinois.

[4] The T.J. O'Brien Lock and Dam approximately 7 miles from Lake Michigan on the Calumet River in Chicago at the head of the Illinois Waterway is named after Congressman O'Brien.

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