How dense should city housing be? A few of Chicago's downtown city blocks, due to their numerous high rises, have some of the highest housing densities in the nation. Chicago's City Council has been pondering for several months whether to allow increased housing density in its other neighborhoods, through an Accessory Dwelling Unit (ADU) ordinance. Ultimately, City Council passed an ADU pilot program. The ordinance would permit "coach houses" and "granny flats" to again be constructed in Chicago housing lots. Several neighboring towns in the suburbs are considering similar measures. Proponents argue that the ADU ordinance would allow for more affordable housing units to be offered on the market, and won't take away from the "feel" of neighborhoods, since those units are often facing the rear of the lots on which they are constructed. The ordinance would also disallow renting those units short term on platforms such as Airbnb and VRBO. Opponents, however, argue that there is no strong mechanism in the ordinance to ensure rents for those units are truly affordable, and are seeking to impose restrictions in the form of maximum rents (a variant of "rent control") to keep their rents low. Economists tend to oppose rent control