After the Supreme Court's 2005 decision in Roper v. Simmons, the minimum age at the time of a crime to be subject to the death penalty is 18.

No one has been under age 19 at time of execution since at least 1964.Since the reinstatement of the death penalty in 1976, 22 people have been executed for crimes committed under the age of 18. 21 of them were 17 at the time of the crime, one, executed in 1999 in Oklahoma, was 16. The last time a juvenile was executed for a crime was in 2003 in Oklahoma.

Before 2005, of the 38 U.S. states that allow capital punishment:

- 19 states and the federal government had set a minimum age of 18

- 5 states had set a minimum age of 17

- 14 states had explicitly set a minimum age of 16, or were subject to the Supreme Court's imposition of that minimum