Cook County Jail

Terrence Anonio James / Chicago Tribune

Loyola criminologist David Olson, a 20-year veteran of the Illinois Criminal Justice Information Authority, just released his analysis of who goes to jail in Cook County and why for 2012 (h/t @roskorpad). It turns out our local jail—and we're talking about jail only here, not prison—has some population numbers that lead the nation.

A lot of people go to jail in Cook County. There was an average daily population of 9,451 in 2012. One jail has occasionally housed more people—Harris County in Texas—but it only an ADP of 8,852, as of last count. (New York City has an ADP of 12,000-17,000, depending on the day. But there's not a single city jail. Those folks are in a bunch of small jails, with none holding more than 3,000).

Totaled up, 62,573 people went to jail in Cook County in 2012. Put another way, about 1.2 percent of everyone in Cook County went to jail last year. About a third were charged with violent crimes (UUW is "unlawful use of a weapon"), accounting for some 22,201 charges. Almost half were in for domestic battery.

That's 9,370 cases of domestic battery in Cook County, in one year.

Overall, domestic battery made up 12 percent of offenses—behind, as you might guess, drug possession. Here's a look at the major offenses (over 700 offenses during the year).

It's a huge jail, but in 2013 it's been pushing its maximum capacity, leading to calls for more electronic monitoring and a cutback in the number of people jailed for nonviolent felonies.