Nineteenth Century
In the early to mid-Nineteenth Century, the abolitionist movement gained momentum in the northeast. In the early part of the century, many states reduced the number of their capital crimes and built state penitentiaries.In 1834, Pennsylvania became the first state to move executions away from the public eye and carrying them out in correctional facilities.
In 1846, Michigan became the first state to abolish the capital punishment for all crimes except treason. Later, Rhode Island and Wisconsin abolished the capital punishment for all crimes. By the end of the century, the world would see the countries of Venezuela, Portugal, Netherlands, Costa Rica, Brazil and Ecuador follow suit. (Bohm, 1999 and Schabas, 1997).

Although some U.S. states began abolishing the capital punishment, most states held onto capital punishment. Some states made more crimes capital offenses, especially for offenses committed by slaves. In 1838, in an effort to make the capital punishment more palatable to the public, some states began passing laws against mandatory death sentencing instead enacting discretionary death penalty statutes. The 1838 enactment of discretionary death penalty statutes in Tennessee, and later in Alabama, were seen as a great reform. This introduction of sentencing discretion in the capital process was perceived as a victory for abolitionists because prior to the enactment of these statutes, all states mandated the capital punishment for anyone convicted of a capital crime, regardless of circumstances. With the exception of a small number of rarely committed crimes in a few jurisdictions, all mandatory capital punishment laws had been abolished by 1963. (Bohm, 1999)

During the Civil War, opposition to the death penalty waned, as more attention was given to the anti-slavery movement. After the war, new developments in the means of executions emerged. The electric chair was introduced at the end of the century. New York built the first electric chair in 1888, and in 1890 executed William Kemmler.

Early and Mid-Twentieth Century
Although some states abolished the capital punishment in the mid-Nineteenth Century, it was actually the first half of the Twentieth Century that marked the beginning of the "Progressive Period" of reform in the United States. From 1907 to 1917, six states completely outlawed the capital punishment and three limited it to the rarely committed crimes of treason and first degree murder of a law enforcement official. However, this reform was short-lived. There was a frenzied atmosphere in the U.S., as citizens began to panic about the threat of revolution in the wake of the Russian Revolution. In addition, the U.S. had just entered World War I and there were intense class conflicts as socialists mounted the first serious challenge to capitalism. As a result, five of the six abolitionist states reinstated their capital punishment by 1920.(Bedau, 1997 and Bohm, 1999)

In 1924, the use of cyanide gas was introduced, as Nevada sought a more humane way of executing its inmates. Gee Jon was the first person executed by lethal gas. The state tried to pump cyanide gas into Jon's cell while he slept, but this proved impossible, and the gas chamber was constructed. (Bohm, 1999)
From the 1920s to the 1940s, there was a resurgence in the use of the capital punishment. This was due, in part, to the writings of criminologists, who argued that the capital punishment was a necessary social measure. In the United States, Americans were suffering through Prohibition and the Great Depression. There were more executions in the 1930s than in any other decade in American history, an average of 167 per year. (Bohm, 1999 and Schabas, 1997)
In the 1950s, public sentiment began to turn away from capital punishment. Many allied nations either abolished or limited the capital punishment, and in the U.S., the number of executions dropped dramatically. Whereas there were 1,289 executions in the 1940s, there were 715 in the 1950s, and the number fell even further, to only 191, from 1960 to 1976. In 1966, support for capital punishment reached an all-time low. A Gallup poll showed support for the capital punishment at only 42%. (Bohm, 1999 and BJS, 1997 )