From Friday, high schools, museums, indoor dining, and gyms in Philadelphia must close, and indoor gatherings with people from more than one household are banned.
This includes weddings and funerals.
The city announced the new restrictions on Friday. Unlike most other state and city lockdown measures announced over the past week, which generally last a month or less, Philadelphia's will be in place until the new year.
High schools and colleges must move to online instruction only. Food outlets will no longer be able to offer indoor dining, but can still offer take-out, delivery, and outdoor dining.
Entertainment and recreational venues such as theaters, movie theaters, museums, libraries, and casinos have to shut.
Gyms and indoor exercise classes will also have to close, although exercise groups and classes will be allowed to continue outdoors.
Stores and beauty salons can stay open at limited capacity, but all visitors have to wear a mask.