02 March 2021 :

Juvenile Life Without Parole: An Overview
The Sentencing Project has published a study on the subject of life imprisonment applied to minors. The study, signed by Josh Rovner, is titled "Juvenile Life Without Parole: An Overview", and begins with the observation that the United States is the only nation that sentences people to life without parole for crimes committed by minors.
Twenty-four states and the District of Columbia have banned life sentences without the possibility of parole for minors. In the other states it is still in force, although in some no one is serving this sentence.
3 sentences, in 2010, 2012 and 2016, led to a limitation of life sentences without parole. In 2010, the Supreme Court of the United States, with the Graham v. Florida, declared unconstitutional to sentence a minor who had not committed a murder to life without parole. That sentence applied to 123 minors, 77 of them in Florida.
In 2012, with Miller v. Alabama, the Supreme Court declared unconstitutional the life sentence without parole imposed on a minor when the law did not provide alternatives, that is, when, in several states, for certain crimes the judge was "obliged" to issue a JLWOP. An estimated 2,500 minors were serving a JLWOP after a murder sentence that year.
In 2016, with the Montgomery v. Louisiana, the United States Supreme Court ruled that Miller v. Alabama was to be applied retroactively.
At the end of 2016, in 29 states and the federal system, there were 2,310 people serving life sentences without parole for crimes committed before the age of 18.
Since then, all "forced" JLWOP convictions have undergone or are undergoing a review procedure. In a few cases, the former minors were also released from prison. For the rest there is no exact count of how many cases have been reviewed, and which sentences have been imposed in lieu.
Another study recently published by the Sentencing Project, "No End In Sight: America's Enduring Reliance on Life Imprisonment" publishes statistics on life sentences in the United States. This study, with data updated to 2020, indicates that 1.465 people would be serving JLWOP, while in about 700 cases the juvenile life without parole sentences would have been canceled, but the prisoners are still awaiting a redetermination of the sentence. In "No End In Sight" it is highlighted that in Georgia 840 people are serving a "normal" life sentence for juvenile offenses.
Among them, 45 were 13 or 14 years old at the time of the crime. In the case of "minors", the "normal" life sentence provides for the possibility of conditional release after minimum detentions ranging from 15 years (Nevada and West Virginia) to 40 years (Texas and Nebraska). Juvenile life sentences without parole, theoretically still in effect today in 26 states, are in practice concentrated in 4 states: Pennsylvania, Michigan, Louisiana, and Florida. These 4 states alone account for 80% of cases.

https://www.sentencingproject.org/publications/juvenile-life-without-parole/