19th century migration tide

The labor force used in the plantation economy in the southern United States is mainly African slaves, not immigrants from Europe. /kloc-In the middle of 0/9th century, the development of capitalism has not yet entered the stage of imperialism. Fascist genocide prevailed in 1930s and 1940s, and most of the materials emphasized immigrants from Europe and America. /kloc-the middle of the 0/9th century was the period when the industrial revolution expanded in the United States. The development of American economy urgently needs labor supplement, which should be the policy of American government to encourage immigration and promote the emergence of immigration wave.