Autoroute 20 is an autoroute in Quebec. It connects Ontario (via Highway 401) with New Brunswick (via Route 2). The section from Autoroute 25 in Longueuil to Route 185 in Rivière-du-Loup is part of the Trans-Canada Highway.
From the A-25 interchange, A-20 goes east through and interchange with Autoroute 30 in Sainte-Julie. It then goes northeast through several interchanges to Saint-Hyacinth, where it meets Routes 137 and 235. From here, it goes east through several more interchanges to Sainte-Hélène-de-Bagot, then goes northeast to Saint-Germain-de-Grantham, and an interchange with Route 122. From here, it is just a short drive northeast to the city of Drummondville, where A-20 meets A-55 (which merges onto A-20), as well as Route 143.
From Drummondville, A-20 goes northeast by Routes 255 and 259 to an interchange with A-955, where A-55 diverges north. A-20 then goes northeast to Laurier-Station, then it continues northeast to Saint-Apollinaire, where it meets Route 273. From here, it continues northeast to Quebec City.