Women are beginning to outpace men, in a least one area: incarcerations.

The Bureau of Justice Statistics (search) reports the number of women in state and federal prison rose by four percent last year, while the number of men increased by less than two percent.

And it says women accounted for nearly one in four arrests.

Study co-author Paige Harrison says the increase is largely due to women's increased participation in drugs, violent crimes and fraud.

Overall, women now make up seven percent of the nation's prison population (search).

The total number of people incarcerated grew nearly 2 percent last year to more than 2,200,000.

Harrison partly blames longer sentences. "Inevitably you're going to have growth," she says, when more people are imprisoned longer.