Here's a non-exhaustive list of what will be normal on Labour Day, and what will not.
• banks
• most government offices and municipal court on Gosford St.
• shopping malls and most retail stores (though some smaller stores may remain open)
• no mail delivery and no service at Canada Post post offices — except for postal counters in drug stores and other private businesses which are open
• most large supermarkets (with a floor space of 375 square meters or more)
• the city's large public markets, such as the Atwater, Jean-Talon and Bonsecours markets.
• the city's major attractions, including the Biodome, Botanical Gardens, Science Centre, Insectarium and Planetarium
• The Montreal Science Centre and IMAX theatre
• The Montreal Museum of Fine Arts, the McCord Museum and the Pointe-a-Callière Museum
• The Montreal Casino (which never closes)
• La Ronde
• most pharmacies (though hours and staff may be reduced)
• grocery stores with a floor space of less than 375 square meters (though again, hours may be reduced)
• garbage pickup generally should continue as usual, though there may be exceptions. (Visit the city of Montreal's web site, or phone Montreal's 3-1-1 hotline, or check with your city or town.)
• Openings for sports centres, arenas, libraries and swimming pools depend on the borough. (Again, check with Montreal's 3-1-1 hotline.)
• parking meters still take money, and all regular parking restrictions apply
• Most SAQ liquor stores will be open — except for those located inside malls and don't have doors that open directly out on to a street or parking lot.
• AMT Commuter trains will run on Sunday schedules on the Deux-Montagnes, Vaudreuil-Hudson and St. Jerome lines. The Mont St. Hilaire, Candiac and Mascouche lines will not run.
• Buses in Montreal, Laval and Longueuil, as well as metros, will run on reduced schedules.