In the early to mid-nineteenth century United States, the abolitionist movement gained support in the northeast. In the early part of the century, many states reduced the number of capital crimes and built state penitentiaries. In 1834, Pennsylvania became the first state to move executions away from the public by carrying them out in correctional facilities. In 1846, Michigan was the first state to abolish the death penalty for all crimes except treason. Later, Rhode Island and Wisconsin abolished the death penalty for all crimes. By the end of the century, the countries of Venezuela, Portugal, Netherlands, Costa Rica, Brazil, and Ecuador followed suit. While some states began abolishing the death penalty, most held onto it. Some states even made more crimes punishable by death, especially those committed by slaves. In 1838, in an effort to make the death penalty more acceptable 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 death penalty 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 were abolished by 1863.

During the Civil War, opposition to the death penalty diminished, as more attention was given to the anti-slavery movement. After the war, new developments in the means of executions emerged. In 1888, the electric chair was introduced in the state of New York. In 1890 William Kemmler became the first man executed by electrocution. Other states followed New York and used the electric chair as the primary method of execution.