There were two “Great Migrations.” The first was during and immediately after WWI, the second, during and after WWII. As whites became more involved in the war effort, blacks moved in to take up jobs formerly held by whites. Both migrations generally involved blacks migrating from the South to the North (notably, New York–the rise of Harlem as an African-American cultural community can be traced to the First Great Migration.)</p>
Here is a basic overview of internal migration, though.</p>
Late 1700s–Americans begin to colonize “Old Northwest” (Northwest Territory, this includes states like Michigan, Ohio, Wisconsin, etc.)</p>
1800s–Americans move westward. This migration is often cited as one of the primary reasons for internal conflicts leading to the Civil War. Territorial disputes (nearly always over the status of slavery in territories) led to many compromises that were only temporarily effective. Important compromises: Missouri Compromise (1820, Missouri admitted as slave state, Maine admitted as free state, slavery banned in the Louisiana territory north of the 36 30 line), Compromise of 1850 (1850, California admitted as free state, slave trade abolished in District of Columbia, Fugitive Slave Law enacted), Kansas-Nebraska Act (1854, allowed the Kansas and Nebraska territories to decided for themselves on the slavery issue. This was the last straw of compromise over slavery before the Civil War. This act essentially repealed the Missouri Compromise.)</p>
(First) Great Migration–explained above.</p>
Dust Bowl Migration–during the 1930s, dust storms swept the lower Midwest and forced thousands of farmers to move westward to find work. Many of these farmers were from Oklahoma and Arkansas (“Okies” and “Arkies”).</p>
(Second) Great Migration–explained above.</p>
Sunbelt Migration–migration during the latter part of the 1900s during which many Americans moved to the South and Southwest (basically, all of the lowest states on a US map). This was facilitated by technological advances including air conditioning and mild winters and migration of baby boomers. Recently, the Sunbelt has been the site of much immigration (legal and illegal) from Latin America.</p>
This is all I can think of off the top of my head. Helping me as much as it’s helping you, I hope!</p>