Europe was a major source of migrants because of the diminishing returns for the middle class in the mainland.
Explanation:
Europe had been colonizing new lands throughout the century and the condition at the home had been worsening for the middle class who sometimes found it better off to either move to a colony or to switch to another nation.
Thus, mass migrations happened especially towards the New World.
This was also the time of migrations to Australia New Zealand and other nations that were settled by Europeans who were in search of a better life.