The areas remain unincorporated largely for two reasons: 1) They are tax base losers, meaning it would cost a nearby city or village more to serve the area than the municipality would get back in taxes, or 2) They are tax winners, in the sense that people living there are happy not to be paying taxes for parks or libraries.

Many of the unincorporated areas also have substandard infrastructure. They might not have sidewalks. Or sewers, using septic systems instead. The streets might not be what a municipality would consider up to code.

Last year, Cook County Board President Toni Preckwinkle suggested creating special service districts that would impose an extra levy on unincorporated areas. That idea didn't fly.

Now, she's putting down the stick and trying a carrot. In her proposed 2013 budget, she allocates $5 million to help fund infrastructure improvements that might make the unincorporated areas more suitable for annexation into an existing suburb.

"I have said that over the next decade we are going to try to eliminate unincorporated Cook County," Preckwinkle told the Sun-Times Editorial Board last week."We spend a lot of resources on the 100,000 people who live there. And we found that one of the principal impediments to incorporation by the nearby towns, cities and villages is the state of their infrastructure. ... So we have created a fund of $5 million to help them upgrade their infrastructure so that they can be annexed by surrounding communities without tremendous costs to those municipalities."

Budget Director Andrea Gibson said the fund will be on a "cash match" basis, meaning the muncipality that does the annexation will be expected to kick in its share.

Of course $5 million is barely a start considering what it would take to get all unincorporated infrastructure up to municipal standards. But Kurt Summers, Preckwinkle's chief of staff, said the county will focus on getting one area at a time up to snuff and annexed, and then refill the coffers.