Today is Thursday, Aug. 2, the 214th day of 2018. There are 151 days left in the year.

On August 2, 1939, Albert Einstein signed a letter to President Franklin D. Roosevelt urging creation of an atomic weapons research program.

In 1610, during his fourth voyage to the Western Hemisphere, English explorer Henry Hudson sailed into what is now known as Hudson Bay.

In 1776, members of the Second Continental Congress began attaching their signatures to the Declaration of Independence.

In 1876, frontiersman "Wild Bill" Hickok was shot and killed while playing poker at a saloon in Deadwood, Dakota Territory, by Jack McCall, who was later hanged.

In 1909, the original Lincoln "wheat" penny first went into circulation, replacing the "Indian Head" cent.

In 1923, the 29th president of the United States, Warren G. Harding, died in San Francisco; Vice President Calvin Coolidge became president.

In 1939, President Roosevelt signed the Hatch Act, which prohibited civil service employees from taking an active part in political campaigns.

In 1943, during World War II, U.S. Navy boat PT-109, commanded by Lt. (jg) John F. Kennedy, sank after being rammed in the middle of the night by the Japanese destroyer Amagiri off the Solomon Islands. Two crew members were killed.

In 1974, former White House counsel John W. Dean III was sentenced to one to four years in prison for obstruction of justice in the Watergate cover-up. (Dean ended up serving four months.)

In 1980, 85 people were killed when a bomb exploded at the train station in Bologna, Italy.

In 1985, 137 people were killed when Delta Air Lines Flight 191, a Lockheed L-1011 Tristar, crashed while attempting to land at Dallas-Fort Worth International Airport.

In 1990, Iraq invaded Kuwait, seizing control of the oil-rich emirate. (The Iraqis were later driven out in Operation Desert Storm.)

In 2000, Republicans awarded Texas Gov. George W. Bush their 2000 presidential nomination at the party's convention in Philadelphia and ratified Dick Cheney as his running mate.