On July 15, Governor Alexander Ramsey appointed Windom to the resulting vacancy, to serve until the legislature elected a replacement.

In the United States Senate, Windom was recognized as a strong advocate of railroad regulation.

The select committee's report was submitted to the Senate on April 24, 1874, and was ordered to be printed the same day.

The convention deadlocked, and after over 30 ballots began to consider choosing a "dark horse" candidate, such as Windom.

[5] On March 7, 1881, Windom resigned from the Senate and was appointed Secretary of the Treasury by Garfield, taking office the next day.

On October 26, he was again elected Senator by the Minnesota Legislature, this time to fill the vacancy left by his own resignation.

He died while giving a speech in the famous Delmonico's Steak House in New York City.

The revenue cutter USS Windom was named for him, as was a World War II Liberty Ship.