The inventory of homes for sale is generally lower early in the year, and grows as listings arrive for the spring and summer selling season. As CAR's chart shows, the city's single-family home inventory has been trending lower and lower for the past five years.

Similar data for the suburbs is not available.

Among the reasons for the dearth of single-family listings are:

•Recent boosts in property taxes and the looming likelihood of further increases make people hesitant to take on a larger home whose tax burden will go up, which keeps them from listing their current home for sale.

•A large proportion of homeowners are so far underwater on the mortgage of their existing home that they can't afford to sell and move.

•Thanks to a years-long bout of low inventory, potential buyers and their real estate agents often aggressively pursue homes that haven't yet been listed for sale.

•The coming mayoral election has Chicagoans uncertain about the next mayor's approach to taxes, limits on gentrification and other issues related to housing.

•Construction of new houses in the city soared a few years ago, resulting in an over-supply in some North Side neighborhoods. That led to lower sale prices which in turn led to builders launching fewer new projects.