Here in the Triangle, Black Widows are very common. Many people have black widows, and they do not even realize it. Black widows avoid light, and they hide in sheltered places. They are active during the night.
I can personally attest to this. When we first moved into our house, I treated the perimeter of our home within the first week of living there. The next day, there were so many dead black widows around the house, I could not believe it. I would never have guessed that there would be so many, if any at all. Our daughter was very young at the time, and she enjoyed playing outside. I felt confident letting her play outside because our house was regularly treated.
The above picture is from our front porch area (I moved some of them closer for picture-taking purposes).
Our general pest control program is designed to kill and protect against black widows spiders (as well as many other pests).