The Development of Labor Unions By summer1 Jan 1, 1834 The National Trades Union The first national union, The National Trades Union, was founded in 1834. Jan 1, 1842 Commonwealth V. Hunt In the 1842 court case Commonwealth v. Hunt, a massachusetts courtruled that unions were legal. Jan 1, 1955 AFL and CIO The AFL and CIO merged in 1955.