Labor Day is a holiday in both the US and Canada.
Banks and government offices will be closed. There will also be no mail delivery from either USPS or Canada Post.
Private businesses, such as stores and the agencies, will close at their own discretion. However, due to capitalism, they will most likely remain open. The SPs will set their own schedule.
In other words, aside from banks and government services, it should be just like any other day.