When did people firstarrive in america

There was limited contact between North American people and the outside world before 1492. Several theoretical contacts have been proposed, but the earliest physical evidence comes from the Norse or Vikings. Erik the Red founded a colony on Greenland in 985 CE.

Explanation:

in 1862, president lincoln's emancipation proclamation opened the door for african americans to enlist in the union army. although many had wanted to join the war effort earlier, they were prohibited from enlisting by a federal law dating back to 1792.

explanation:

necessary and proper clause. the congress shall have power to all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states, or in any department or officer thereof.