On this day, Dec. 6

1865 The 13th Amendment to the U.S. Constitution, abolishing slavery, was ratified as Georgia became the 27th state to endorse it.

1917 Some 2,000 people were killed when an explosives-laden French cargo ship, the Mont Blanc, collided with the Norwegian vessel Imo at the harbor in Halifax, Nova Scotia, setting off a blast that devastated the Canadian city.

1954 One hundred eighteen business firms, schools and hospitals 80 years or older were honored by the Pittsburgh Chamber of Commerce at its 80th anniversary dinner, attended by 900 persons in the William Penn Hotel. The speakers were William Block, publisher of the PostGazette, the city’s oldest (1786), and Alan M. Scaife, chairman of the board of the Scaife Co., second oldest (1802). Each received a special plaque.

1973 House minority leader Gerald R. Ford was sworn in as vice president, succeeding Spiro T. Agnew.

1991 South African leader Nelson Mandela visited the city.

2009 Penn Hills police officer Michael Crawshaw was killed waiting for back-up outside a home where shots were reported being fired. The shooter killed a man inside the home and then proceeded to riddle Crawshaw’s vehicle with bullets. Some items are from Stefan Lorant’s “Pittsburgh: The Story of an American City” (digital.library.pitt.edu/chronology).

— Compiled by Rick Nowlin

Today’s birthdays: Comedy performer David Ossman, 85. Actor Patrick Bauchau, 83. Country singer Helen Cornelius, 80. Actor James Naughton, 76. Former Transportation Secretary Ray LaHood, 76. R&B singer Frankie Beverly (Maze), 75. Former Sen. Don Nickles, R-Okla., 73. Actor JoBeth Williams, 73. Actor Tom Hulce, 68.

Actor Wil Shriner, 68. Actor Kin Shriner, 68. Actor Miles Chapin, 67. Rock musician Rick Buckler (The Jam), 66. Comedian Steven Wright, 66. Country singer Bill Lloyd, 66. Rock musician Peter Buck (R.E.M.), 65. Rock musician David Lovering (Pixies), 60. Actor Janine Turner, 59. Rock musician Ben Watt (Everything But The Girl), 59. Writer-director Judd Apatow, 54. Rock musician Ulf “Buddha” Ekberg (Ace of Base), 51. Writer-director Craig Brewer, 50. Actor Colleen Haskell, 45. Actor Lindsay Price, 45. Actor Ashley Madekwe, 40. Actor Nora Kirkpatrick, 37. Tennis player CoCo Vandeweghe, 30. NBA star Giannis Antetokounmpo, 27. Thought for today: “Americans have always been able to handle austerity and even adversity. Prosperity is what is doing us in.”