On October 19, 2015, after the longest official campaign in over a century, Trudeau led the Liberals to a decisive victory in the federal election. The Liberals won 184 of the 338 seats, with 39.5% of the popular vote, for a strong majority government; a gain of 150 seats compared to the 2011 federal election.
On November 5, 2015, during the first Liberal caucus meeting since forming a majority government, the party announced that it would reinstate the mandatory long-form census that had been scrapped in 2010, effective with the 2016 census.