May 1911

Thursday 11:

The United States becomes a signatory to the Buenos Aires copyright treaty.

Monday 15:

The United States Supreme Court declares Standard Oil to be an "unreasonable" monopoly under the Sherman Antitrust Act and orders the company to be dissolved.

Tuesday 23:

Dedication ceremony for the New York Public Library.

Wednesday 24:

The New York Public Library opened.

Tuesday 30:

At the Indianapolis Motor Speedway, the first Indianapolis 500 ends with Ray Harroun becoming the first winner of the 500-mile auto race in his Marmon Wasp.