Robyn Allen saw her daughter for the first time in two years from across the yard of Oklahoma’s largest women’s prison, the Mabel Bassett Correctional Center.

Because the two were serving time for the same 2013 methamphetamine case, they weren’t supposed to communicate. But as Allen’s daughter, Cherise Greer, was being loaded into a van on her way to another prison this summer, the guard turned away.

Greer, in an orange prison uniform, called out: “I love you.”

“She told me she loved me and said, ‘Mom, please don’t cry,’ ” said Allen, 52, wiping away tears as she recalled the moment.

When their paths crossed in June, Allen and her daughter were among more than 3,000 women serving time in Oklahoma, which for 25 years has led the nation in locking up women. The state imprisons 151 out of every 100,000 women, according to the U.S. Bureau of Justice Statistics – more than double the national rate.

In partnership with The Frontier, an Oklahoma journalism startup, Reveal from The Center for Investigative Reporting spent more than a year unearthing the causes. The reporting included obtaining a decade’s worth of state prison data never before analyzed by the state itself.

The most common reason women end up in prison: drug possession. Oklahoma dealt out ever-longer sentences for these women, even as other conservative states reduced drug sentences as part of criminal justice system overhauls.

The burden of the state’s high incarceration rate falls hardest on women of color. Black women are incarcerated at about twice the rate of their representation in the state’s adult population, Reveal’s analysis shows. For Native American women, the disparity is almost three times their share of the population.

At a recent national summit on female incarceration, Oklahoma Gov. Mary Fallin called the No. 1 ranking “a dubious honor … not something I’m proud of.”

Reveal found the average sentence length for drug crimes differs markedly throughout the state, with more rural counties having the highest female incarceration rates.

Go to News On 6 partner The Frontier for more on this and other stories.