The One Big Union (OBU) was a militant left-wing industrial union based primarily in Western Canada. Launched formally in Calgary on June 4, 1919, the OBU, after a spectacular initial upsurge, lost most of its members within a few years. It eventually merged with the Canadian Labour Congress in 1956.

The Trades and Labor Congress of Canada was a Canada-wide central federation of trade unions from 1886 to 1956. It was founded at the initiative of the Toronto Trades and Labour Council and the Knights of Labor. It was the third attempt at a national labour federation to be formed in Canada: it succeeded the Canadian Labour Union which existed from 1873 to 1877 and the Canadian Labour Congress which held only one conference in 1881.