Raw Data: The Homeless Rate in Big Cities

The number of homeless rose to 59,000 in Los Angeles County this year. We don’t yet have estimates for all cities, but here’s how a selection of big cities did last year. Note that these are actually the homeless rates for the counties which contain each city (i.e., Phoenix is actually Maricopa County, Chicago is Cook County, etc.):
What surprises me is the huge difference across cities. In New York and Washington DC, nearly 1 percent of the population is homeless. In Chicago the number is 0.02 percent. That’s a difference of almost 50x. What kinds of policies can possibly account for such a vast disparity? Or is it mostly a statistical artifact of how the counts are conducted in each city? Or the inevitable result of high homeless rates following high housing prices?