What contributed to the growth of Trade Unions in the late 19th century?

Many factors

Explanation:

As an organized movement, trade unionism (also called organized labor) originated in the 19th century in Great Britain, continental Europe, and the United States. In many countries trade unionism is synonymous with the term labor movement. Smaller associations of workers started appearing in Britain in the 18th century, but they remained sporadic and short-lived through most of the 19th century, in part because of the hostility they encountered from employers and government groups that resented this new form of political and economic activism. At that time unions and unionists were regularly prosecuted under various restraint-of-trade and conspiracy statutes in both Britain and the United States.

While union organizers in both countries faced similar obstacles, their approaches evolved quite differently: the British movement favored political activism, which led to the formation of the Labor Party in 1906, while American unions pursued collective bargaining as a means of winning economic gains for their workers.