If you walked around downtown Ann Arbor today, you saw ads for the new AnnArbor.com marked in sidewalk chalk on the sidewalk. They were outside my office at Fifth and Liberty - variously "where Primo Coffee used to be", or "where Sun Bakery used to be", depending on your historical reference point. Though they look like spray paint, they are actually chalk, and they will wash away harmlessly in the next rain.

I heard a bit of grumbling about this, including people wondering whether it was OK to put chalk on the sidewalk. Since I have kids who have sidewalks in front of their house and who like to put chalk on it from time to time, it seemed prudent to be certain that there wasn't something wrong with that too. Here's what I found.

The Ann Arbor City Code is online. The relevant section, as far as I can tell, is the new graffiti ordinance, passed in January 2009. It reads (chapter 106, section 9:6):

(1) "Graffiti" constitutes a public nuisance and means any mark or marks on any surface or structure made without the prior permission of the property owner and made in any manner, including but not limited to, writing, inscribing, drawing, tagging, sketching, spray-painting, painting, etching, scratching, carving, engraving, scraping, or attaching. Chalk marks on sidewalks are not "graffiti." Graffiti does not include any posting of posters as permitted under Chapter 82, Section 7:102(3).

If you walk across the University of Michigan campus - especially in front of the Michigan Union, or across the Diag, you see a lot of sidewalk chalk. It's the main way that student groups mark their place for voting for student government, and it's a colorful and cheap way to get your message across. Besides, it's incredibly easy to clean up.

A 2002 Michigan Daily editorial, "Chalk is cheap: University should never prohibit student chalking", puts forth the case:

What would this university's campus be without colored chalk messages scrawled all over the place? Sans the efforts of chalk-crazy groups like the Coalition to Defend Affirmative Action By Any Means Necessary, groups of prospective students touring the campus would be met with far more drab surroundings. And as annoying as the chalking gets around Michigan Student Assembly campaign time, it's visible - which means it gets the job done.

Sadly, these multi-colored announcements, at some colleges and universities, are becoming restricted and perhaps are on their way to being outlawed altogether. The University of Michigan should not join in on this slippery slope to silencing student voices.

Sidewalk chalk is also a great tool for low cost, temporary public art projects. The one that comes to mind happened in Grand Rapids this year, where Rob Bliss organized a massive Chalk Flood and gave away 30,000 sticks of chalk for people from the city to decorate a public plaza. This Grand Rapids Press story about the Chalk Flood tells the story:

GRAND RAPIDS -- Downtown flooded Saturday without a drop of rain or a dam bursting. Instead, sidewalks were awash with color as thousands of children, college students, adults and senior citizens descended on a sunny, warm central city for the first-ever Grand Rapids Chalk Flood, a free event organized by 20-year-old Rob Bliss.

"I'm really happy. It's such a beautiful day, easily the best day in all of April," said Bliss, as artists of all shapes, sizes, ages and colors were spilling over from Rosa Parks Circle on to sidewalks throughout downtown.

Even more amazing is the work of Ann Arbor born artist Kurt Wenner, who creates the illusion of 3-D images in his anamorphic street paintings.

So, the next time you see a bit of chalk on the sidewalk, think about what kind of street art it could be - and rest assured that, at least in Ann Arbor, sidewalk chalk is not a crime.