The Alley Green

The last time I was downtown, I walked past this imprint in the concrete at the opening of the alley between N. LaSalle St. and N. Wells St. near the north curb of W. Washington St.

"City of Chicago Green Alley," it says, plus glyphs that seem to be the Earth, the Sun and one of those curly-toed shoes that Santa's elves wear. Also: "Richard M. Daley, Mayor." (Will he miss being able to stamp his name on public works? Maybe. Note that he's careful to distinguish himself from that other long-serving mayor, Richard J.)

So it's a green alley. It's hard to tell just by looking at it. Literally speaking, it looks like many Chicago alleys.

What's a green alley, then? "Chicago has approximately 1,900 miles of alleys and about 3,500 acres of paved surface, city estimates show," said the Tribune a few years ago. "That's equivalent to about 11 Grant Parks. A 2005 Tribune study found more than 90 percent of the city's blocks are bisected by alleys, making Chicago the alley capital of the world.

"Chicago has so many of these little pathways because city planners saw how East Coast cities such as New York and Boston had garbage overflowing onto streets, said Perry Duis, an urban history professor at UIC. Chicago planners didn't want a similar situation, so they created easements behind homes for garbage.

"Ninety-eight Chicago alleys have been deemed green alleys because they incorporate specific environmentally friendly materials or design, such as a permeable pavement, recycled materials or light-colored concrete, according to... the Chicago Department of Transportation.

"The city started its green alley pilot program in 2006 to improve stormwater drainage, reduce heat, promote recycling and conserve energy in alleys. The program began with five alleys, and about 30 to 45 of the city's thousands of alleys have become green each year since."