What was the theory about Native American migration to the Americans that was believed and taught for a long time

The "Clovis first theory" refers to the 1950s hypothesis that the Clovis culture represents the earliest human presence in the Americas, beginning about 13,000 years ago; evidence of pre-Clovis cultures has accumulated since 2000, pushing back the possible date of the first peopling of the Americas to 33,000 years ago.

Explanation:

the labor movement in the united states grew out of the need to protect the common interest of workers

for those in the industrial sector organized labor unions fought for better wages reasonable hours and safer working conditions

  in the 19th century trade unionism was mainly a movement of skilled workers.

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