The Long Beach pier auditorium disaster, sometimes known as the Empire Day tragedy, occurred on Saturday, May 24, 1913, in Long Beach, California, United States, when the top level of the Pine Avenue Pier collapsed near the entrance to the municipal auditorium.

[3] In 1905 the pier added an auditorium "designed by renowned California architect Joseph Cather Newsom and featured an assembly space large enough to accommodate 5,000, multilevel outdoor promenades and two towers framing the central section of the building....a horrendous structural failure caused by wood rot" killed and injured almost 200 people when the floor collapsed.

[4] The pier was especially crowded that day because of an Empire Day celebration of the Commonwealth on the anniversary of Queen Victoria's birthday, which had attracted tens of thousands of British expatriates from around Southern California.

[3][5] The California State Supreme Court later found the city of Long Beach "negligent for the rotted wooden pier pilings".

[1] After the upper deck collapsed in 1913, the city wanted to demolish the entire structure but residents lobbied for a restoration, and a reconstructed Pine Avenue Pier opened in 1915.