The history of capital punishment in the United States is one in which the practice has become more and more restricted over time.
In early America, capital punishment was not a controversial issue. Few people had any qualms about executing criminals of various sorts. Since then, the trend has generally been towards limiting the use of the death penalty. First, there were movements to stop public executions. Later, reformers started to try to make execution ever more humane. This started with the use of the electric chair and has moved to the point where lethal injection is the most commonly used method of execution since it is believed to be the most humane.
There has long been some degree of opposition to the whole idea of the death penalty. This has become stronger in recent years. The death penalty was abolished for a short time in the 1970s, but only because the Supreme Court ruled that it was being applied arbitrarily, not because the punishment itself was unconstitutional. Today, there is a great deal of controversy over the death penalty both because of the issue of cruelty and because of questions about whether it can be administered fairly.