Lots and lots of parking lots. That has been a major issue in Spokane as historic buildings have been razed in the past - just look back to the Spokesman's "Then & Now" on the Rookery Block. We know they create economic dead zones but it's slowly getting better since City Council passed a moratorium on open surface parking lots in the downtown core five years ago.
While cities make efforts to manage parking differently, there's certainly a correlation between healthier and cleaner communities. This quick video by the Institute for Transportation and Development Policy (ITDP) and Streetfilms explains the importance of the issue. It also reminds me of Schoolhouse Rock, so win-win.