On this day, Dec. 7

1787 Delaware became the first state to ratify the U.S. Constitution.

1907 Pittsburgh officially annexed Allegheny City and became a city of 521,000 population, the sixth-largest in the nation.

1941 Japan launched a surprise attack on the U.S. Navy base at Pearl Harbor in Hawaii as part of its plan to conquer Southeast Asian territories; the raid, which claimed some 2,400 American lives, prompted the United States to declare war against Japan the next day. 1972 America’s last moon mission to date was launched as Apollo 17 blasted off from Cape Canaveral.

2001 Carnegie Mellon University and the University of Pittsburgh began a $600 million collaboration called the Pittsburgh Life Sciences Greenhouse for biotechnology research and development. Some items are from Stefan Lorant’s “Pittsburgh: The Story of an American City” (digital.library.pitt.edu/chronology). — Compiled by Alyssa Brown

Today’s birthdays: Political philosopher Noam Chomsky, 90. Baseball Hall of Famer Johnny Bench, 71. Singer-songwriter Tom Waits, 69. Basketball Hall of Famer Larry Bird, 62. Former “Tonight Show” announcer Edd Hall, 60.

Thought for today: “Any frontal attack on ignorance is bound to fail because the masses are always ready to defend their most precious possession — their ignorance.” — Hendrik Willem van Loon, Dutch-American journalist and lecturer (1882-1944)