The number of women in state prisons has grown exponentially in the past three decades, growing at more than twice the rate as the male population, according to a report from the Women's Prison Association.

The Associated Press reported May 21 that the report found that the female prison population grew 757 percent between 1977 and 2004, while the male prison population grew 388 percent.

In the Mountain States of the U.S., the increase was 1,600 percent. In Colorado, for example, the female prison population was 72 in 1977; by 2004, it was 1,900. Oklahoma had the highest per-capita imprisonment rate for women: 129 per 100,000 population.

Women made up more than 10 percent of the prison population in Idaho, Wyoming, Montana, Oklahoma, North Dakota, and Hawaii. By contrast, only 3.2 percent of inmates in Rhode Island were women; the report said that the rate of female incarceration has dropped in the Northeast even as it has increased elsewhere in the nation.

Nationally, there were 96,125 women in prison in 2004, up from 11,212 in 1977.

Most of the increases in female imprisonment can be traced to the war on drugs, the report said. More women are being sent to prison for drug offenses -- notably methamphetamine use -- while convictions for violent crimes have fallen. Experts called for alternative sentencing for female prisoners, including addiction treatment for drug offenders.