The pot of many different cultures. For example,

The Great Migration, a
relocation of millions of African-Americans from the southern rural areas to
the bustling cities to the north and west. Desiring better economic
opportunities and lesser segregation, many African-Americans went north. There,
they found cities with the need for industrial workers, and took advantage of
that. Cities such as New York and Chicago saw their African-American population
expand explosively, causing people to fight over living space, as well as deal
with racism and prejudice. African-Americans began to confront new challenges
in their daily lives, economically, politically, and socially, creating a new
city within cities.

             During World War
I, the first great movement occurred, with 454000 African-Americans moving
north. This was immediately followed by 1.2 million in the 1920s and 1930s. In
the 1940s and 1950s, over 3.3 million African-American citizens had left for
northwestern cities. The motivation behind these mass migrations were an
amalgamation of the desire to get away from poor economic and societal
conditions for African-Americans in the south, and the white supremacist
mindset greatly restored across the south after the Civil War Reconstruction
period. After the emancipation from slavery, many African-Americans had
suffered in an economy that they could rarely advance in, and when faced with
better economic opportunities in the north, chose to take them.

            Many African-Americans had left the south through boat, bus,
or train, with few going through cars or horse-drawn carriages. By the 1920s, the
African-American population of major cities such as New York, Chicago, Detroit,
and Philadelphia, had grown massively. However, this also resulted in
competition for employment and living space. Segregation was not legalized in
the north, but racism was commonplace, with some neighborhoods creating rules
that required white property owners to never rent or sell to African-Americans.
As a result, African-American and white relations continued to worsen,
especially due to activity from the Ku Klux Klan, which began one of the largest
periods of racial friction in the United States.

            Overall, the Great Migration had an enormous impact on
the United States. It changed some all-white communities into a great melting
pot of many different cultures. For example, Harlem in New York City, which
would come to house some 200000 African-Americans. It had a tremendous impact
on the culture of the early-mid 1900s, and became an era of increased activism
by African-Americans, due to their unfair treatment in the south. Although it
slowed down quite a bit during the Great Depression, the impact it had on
cities was already prominent.