Tourangeau attempted to have the walls separating Quebec City's Upper Town and Lower Town demolished, although his efforts failed.
He served another term as mayor in 1870; after the end of his term, Tourangeau and several of his fellow councillors continued to occupy city hall, claiming that the election was invalid.
They were eventually forced to surrender after supplies were cut off.
He was elected to the House of Commons in an 1870 by-election, after Pierre-Gabriel Huot resigned his seat.
He was reelected in 1872 but did not run in 1874.
He ran unsuccessfully in an 1877 by-election against Wilfrid Laurier.
He returned to his notary practice.
He was named postmaster for Quebec in 1883 and served until his death in 1894.