They have a division of specialization. I'm pretty sure thats the answer.
Answer: In the span of about 50 years, there were about 20 major and minor population migrations.
Explanation:
In the second half of the nineteenth century until the beginning of the 20th century, over 12 million migrants immigrated to the United States. The reasons were mostly economic in nature but also religious.
In 1860, a large number of Poles and Russians came for the aforementioned reason. These two national groups' continuous settlement can be followed until 1914 when about 2 million Poles and Russians immigrated.
In this context, we will also mention one event that caused population movements in the United States. In 1863, the Union banned slavery and allowed African Americans to join the military, causing large-scale migrations of the African-American population to the north.
Around 1880, primarily due to Italy's poor economic situation, a huge number of Italians immigrated to the united states. Since then, more intensive settlement of Italians in the unification of the state has begun.
The southern(who were previously Confederate) states all wrote new Constitutions and swore loyalty to the Union by 1877. Also, the 13th amendment(which states no slavery n<span>or involuntary servitude</span> is allowed unless punishment... in u.s.), 14th amendment(forbids states to restrict simple rights of citizens etc,), and 15th amendment(citizens in U.S. cannot be denied due to race, color, etc. to vote) were acknowledged and remained after the reconstruction. Former slaves also had a new life ahead of them: they could now be educated, choose who they wanted to marry, and choose jobs. Unfortunately, the reconstruction didn't heal African American/ white man wounds; and even though there were laws for equality, for many upcoming years, many black people still had many problems with white people who still believed they were somehow superior.
It would be "<span>Making a contact" that is not one of the most common uses of Twitter, since Twitter is used mostly to interact with people you already know, or who you "follow". </span>