One idea is higher taxes on vacant properties
The Expanding Housing Choice paper I previously reviewed goes on to recommend a lot of strategies CMAP and its existing partner organizations (including Metropolitan Planning Council and South Suburban Mayors and Managers Association) can adopt or expand, so you should read the paper if you want to know how to get involved.
I’m highlighting one section of their recommendations because it meshes deeply with what I’ve been promoting on Chicago Cityscape: vacant and abandoned properties.
“Little research has been done on re-classifying vacant and blighted buildings into higher property tax rates to encourage property owners to maintain and return the buildings to productive uses, a potential strategy in areas with stronger underlying demand.”

Taxing owners of vacant land and buildings is a technique used in Washington, D.C. to incentivize finding tenants. In fact, vacant land in D.C. is taxed nearly six times higher than residential property, and there’s a one-year exemption for owners “actively seeking in good faith to rent or sell the property”. (The exemption for commercial property is two years.)
An Illinois legislator wants to eliminate a tax break that landlords of vacant commercial property are taking advantage of. This, from DNAinfo:
Current state law allows the owners of properties that become vacant unexpectedly to ask tax officials for a break on their bill — as long as they are doing everything possible to find a new tenant for the store or office.
But there are troubled properties that have received the break for decades — when, in some cases, the owners should be paying the property’s tax bill in full, Martwick said.
The bill, HB4363, has been dead since January 2017, when it was marked as “session sine die” in the Illinois House.