I found this interesting. Researchers modeled the spread using movement patterns from 98 million cell phones. 10% of the locations we go to account for 85% of the infections.

Among the culprits: restaurants, gyms, hotels, houses of worship.

Socioeconomic class matters too, because lower income folks are less likely to work from home and have adverse mobility patterns. Some of the locations they go to are more crowded to (e.g., supermarkets in poor neighborhoods).

According to researchers, reducing peak capacity at the offending venues to 20% (creating much more spacing) would reduce infections by more than 80%