answer:I work in San Francisco, so they are all around me as I walk the two blocks from the train to my office. We used to call them “hobos”. And I often saw them down near the train tracks and on skid row in San Francisco. Calling it “an influx” is a bit of overstatement. In terms of absolute numbers, it has gone up, but not necessarily in percentage terms. In many ways they are just more visible than they ever were before. We had whole areas south of Market Street with old industrial buildings that are now replaced with million dollar condos. The homeless have been moved out of old hiding places and out onto heavily traveled streets. For causes: an economy without many jobs for unskilled workers, income inequality with the top 1/10th of 1% controlling more than the bottom 50%, lack of Congressional support for the VA and housing for veterans.