Detroit
The city has numerous neighborhoods consisting of vacant properties resulting in low inhabited density in those areas, stretching city services and infrastructure. These neighborhoods are concentrated in the northeast and on the city's fringes. A 2009 parcel survey found about a quarter of residential lots in the city to be undeveloped or vacant, and about 10% of the city's housing to be unoccupied. The survey also reported that most (86%) of the city's homes are in good condition with a minority (9%) in fair condition needing only minor repairs.

Q: How many of Detroit's residential lots are are underdeveloped?
a quarter