Seattle is having the same problem. I live in a suburb of Seattle and about twice a year Hubby and I attend a Mariner's baseball game. We have been doing this for years.
Last year, as I was driving down the street that leads to Safeco Field, I went under an overpass and was shocked at the number of tents and homeless guys living under the overpass. It had crossed the street and was cropping up in a enpty lot. It was not there last year; but, now they have this problem.