I see a lot of mattresses when I walk around my San Francisco neighborhood of Potrero Hill. I don’t know where they came from, how they got here or who slept on them. When I see a mattress I use the SF311 App to notify the city. Sometimes the mattress can stay in the same location for days, or even weeks, before being carted away by city workers. In the meantime they get moved around, piled with trash and perhaps used again as sleeping places.