1886: The New York legislature establishes a commission to determine "the most humane and practical method known to medical science of carrying into effect the sentence of death." The panel opposes execution by hanging because of its frequent bungling and tendency to degenerate into an ugly public spectacle. After considering alternatives such as electrocution, cyanide poisoning and intravenous injection of morphine, it recommends electrocution.

1890: First use of the electric chair. Ax murderer William Kemmler is electrocuted in the state prison at Auburn, N.Y., with 12 physicians in attendance.

1924: First use of the gas chamber occurs in Nevada.

1930-1967: A total of 3,829 Americans are executed, an average of 10 per year. Executions peak in 1935, when 199 are put to death, then decline during 1950s and 1960s. In 1967, executions cease, pending outcome of legal challenges to death penalty.

1972: By a vote of 5 to 4, U.S. Supreme Court declares death penalty unconstitutional as imposed by widely varying state laws. Capital punishment is suspended.

1976: Supreme Court in a 7 to 2 vote reinstates death penalty, declaring revised laws in Florida, Georgia and Texas constitutional.

1977: Oklahoma, followed quickly by Texas, becomes first state to adopt lethal injection as method of execution.

1977: Gary Gilmore is executed by firing squad in Utah, ending a 10-year moratorium on capital punishment.

Dec. 7, 1982: First execution by lethal injection. Charles Brooks is put to death in Texas.

1982-1990: A total of 142 Americans are executed -- 82 in the electric chair, 55 by lethal injection, 4 in the gas chamber and 1 by firing squad.

Nov. 29, 1990: Pennsylvania becomes 20th state to enact a death penalty law specifying lethal injection.

Dec. 17, 1990: Leonel Herrera is scheduled to be executed by lethal injection in Texas. Barring a last-minute reprieve, he would become the 143rd American put to death since 1976.