In 1856, he was elected to the municipal council of Quebec City and served as mayor from 1858 to 1861. In 1857, he was elected
Member of Parliament for
Dorchester in the
Legislative Assembly of the Province of Canada as a member of the
Conservative Party. He held various positions in
Cabinet, including Solicitor General (1864–66),
Postmaster General (1866–67),
Secretary of State for Canada (1867–69),
Superintendent-General of Indian Affairs (1868–69),
Minister of Public Works (1869–73) and acting
Minister of Militia and Defence (1873). Langevin also attended all three conferences leading to
Confederation. He left politics in 1873 due to his role in the
Pacific Scandal. In
1871, he was elected to the
Legislative Assembly of Quebec in the provincial electoral district of
Québec-Centre. At the time,
dual mandates were still allowed. He served one term, until 1874. In 1876, he was re-elected in the riding of
Charlevoix. His opponent contested the election and it was declared invalid, but he won the
subsequent by-election in 1877. He was defeated in
Rimouski in 1878 but elected by acclamation in the riding of
Trois-Rivières in the same year. Langevin became Minister of Public Works again in 1879. He lobbied behind the scenes against the hanging of
Louis Riel in 1885 and was one of the few Conservative Members of Parliament to survive the resulting backlash in the province of
Quebec in 1887. He was promised the post of
Lieutenant Governor of Quebec by the new Conservative Prime Minister
John Abbott if he resigned as Minister of Public Works. Langevin stepped down in 1891 but Abbott appointed
Joseph-Adolphe Chapleau instead. That year, Langevin was implicated with
Thomas McGreevy in what became known as the "McGreevy-Langevin scandal" over kickbacks to McGreevy associated with federal contracts granted to him by the Department of Public Works overseen by Langevin. He retired to the backbenches and then left politics in 1896. Outside politics, he was previously a newspaper editor. ==View on Indigenous Canadians==