Capital punishment in the United States
In the 1970s, Oklahoma passed the first law that allowed executions by lethal injection.  This was a practical decision: Oklahoma's old electric chair would need expensive repairs, and building a gas chamber would cost over $200,000.  However, executing a person by lethal injection would only cost $10 to $15 per person.  Lethal injection grew more and more popular in death penalty states.  It was viewed as less painful, with less suffering, than the electric chair or gas chamber.  Texas was the first state to execute someone by lethal injection, in 1982.  Over the next 30 years, all of the death penalty states passed laws making lethal injection their first-choice (or only) method of execution.