On this day, Dec. 20

1803 The Louisiana Purchase was completed as ownership of the territory was formally transferred from France to the United States.

1860 South Carolina became the first state to secede from the Union as all 169 delegates to a special convention in Charleston voted in favor of separation.

1864 Confederate forces evacuated Savannah, Ga., as Union Maj. Gen. William T. Sherman nearly completed his “March to the Sea.”

1963 The Berlin Wall was opened for the first time to West Berliners, who were allowed one-day visits to relatives in the Eastern sector for the holidays.

1987 More than 4,300 people were killed when the Doña Paz, a Philippine passenger ship, collided with the tanker Vector off Mindoro island.

1989 The United States launched Operation Just Cause, sending troops into

Panama to topple the government of Gen. Manuel Noriega.

1995 An American Airlines Boeing 757 en route to Cali, Colombia, slammed into a mountain, killing all but four of the 163 people aboard.

1999 The Vermont Supreme Court ruled that gay couples were entitled to the same benefits and protections as wedded heterosexual couples.

2001 The U.N. Security Council authorized a multinational force for Afghanistan.

2002 Trent Lott resigned as Senate Republican leader two weeks after igniting a political firestorm with racially charged remarks.

2005 A federal judge ruled that “intelligent design” could not be mentioned in biology classes in a Pennsylvania public school district, delivering a stinging attack on the Dover Area School Board.

2017 Cardinal Bernard Law, the disgraced former archbishop of Boston, died in Rome at the age of 86; his failure to stop child molesters in the priesthood had triggered a crisis in American Catholicism. Today’s birthdays: Original Mouseketeer Tommy Cole (TV: “The Mickey Mouse Club”), 82. Rock musician-music producer Bobby Colomby, 79. Rock musician Peter Criss, 78. Former U.S. Agriculture Secretary Sonny Perdue, 77. Psychic/illusionist Uri Geller, 77. Producer Dick Wolf (“Law & Order”), 77. Rock musician Alan Parsons, 75. Actor Jenny Agutter, 71. Actor Michael Badalucco, 69. Actor Blanche Baker, 67. Rock singer Billy Bragg, 66. Actor Joel Gretsch, 60. Country singer Kris Tyler, 59. Rock singer Chris Robinson, 57. Actor Nicole deBoer, 53. Movie director Todd Phillips, 53. Singer David Cook (“American Idol”), 41. Actor Jonah Hill, 40. Actor Bob Morley, 39. Singer JoJo, 33. Actor Colin Woodell, 32.