Today’s arrests of protesters in downtown Chicago, and the drumbeat of businesses announcing they will close shop at the end of this week, casts further doubt on Chicago's projection that the two-day NATO summit will be a money maker.

“We stand to benefit a little if things go well, but we could get a black eye if they don’t,” says Alan Sanderson, an economist at the University of Chicago.

Alluding to the 1968 Democratic National Convention in Chicago, Sanderson states that disaster could happen if police and protesters get out of hand. Otherwise, Sanderson contends people will mainly be inconvenienced and that the economic effects will be marginal.

Chicago Mayor Rahm Emanuel touted the upcoming summit, scheduled for May 20 and May 21 at McCormick Place convention center, as a chance to raise the city’s profile and boost tourism. A report by World Business Chicago, the city’s non-profit business recruitment arm that is also running summit preparation, pushed that idea.

Commissioned for the non-profit by Deloitte consulting, the study, released April 30, claimed the NATO summit could bring in $128.2 million for the city. The figure largely comes from money that hotels will make by hosting diplomats and their staff.

Sanderson says the statistic does not account for the “substitution effect” – i.e. that if not for the NATO summit, other Windy City visitors would probably stay at hotel rooms. Also, Sanderson gave an argument that Chicago community groups also give – money the city raised for NATO planning and security is money that won't go towards schools, infrastructure or a host of other public goods.

Events of the past week also throw the Deloitte/World Business’s report conclusions into question:

* The city announced last week that Lake Shore Drive, parts of the Interstate 55, and numerous roads by McCormick Place will shut down. Also, Metra announced today that they would cancel 11 trains on Monday, May 21.

* The Adler Planetarium, Shedd Aquarium, and Art Institute of Chicago will all be closed for three days for the NATO summit weekend.

* Occupy Chicago and other advocacy groups planned a week’s worth of protests. Just today, advocates for the Catholic Workers movement occupied the lobby of President Barack Obama’s campaign headquarters, leading to eight arrests.

The anticipated protests mean a dramatically increased police presence throughout downtown Chicago.

They also caused some of the city’s biggest downtown employers, including Blue Cross Blue Shield and the American Medical Association, to inform workers that they should not show up to work Friday and Monday. The numerous shut downs come amid Emanuel’s assertion that Chicago will be “open for business” during the summit.