We have plenty of them around here. The other day my wife asked me what happens if a black widow bites you. I told her that it is rarely fatal, but leads to a lot of very painful symptoms. Then I asked her why, to which she replied that one had just bitten her. She had been moving some potted plants in the back yard and picked up a hitchhiker on her arm. She then smashed it on her arm. It turns out that she wasn't actually bitten, but was a little freaked out because she had to smash one on her arm.
I get them in my garage all the time, and when I walk through their webs that they will spin overnight by my car, I have to do a quick check to make sure I don't have one hanging on me. If I do, I quickly remove it.