With millions of people throughout the country out shopping on Black Friday, the deals offered by stores like Wal-Mart, Target, and many others is a positive externality to many smaller stores and restaurants. Black Friday causes a large boost in traffic for restaurants and other stores located near malls and shopping centers. It has also become a positive externality for UPS and FedEx as a large portion of the Black Friday deals are now offered online and cause an increase in shipments.
Although it is a positive externality for many stores and companies, for me it is more of a negative externality. I have never been shopping on Black Friday, but every year I hate having to drive anywhere on this day because a 10-minute drive can turn into a 30-minute drive waiting in traffic because of all of the people out shopping.