When the United States was a great industrial nation that was underpopulated, immigrants came from Western and Eastern Europe to work in steel mills, factories, on railroads, etc. Many earned enough money to buy homes and contribute to the economy after becoming citizens. There was no welfare in the early 1900s, so they placed no drain upon the government.
Nowadays, there is little that is manufactured in the United States. So, many of the immigrants who come to work in the U.S. work at lower paying jobs rather than ones that will elevate them economically. Often these immigrants are not citizens, so they deduct for their dependents, then return to their country without contributing much to the American economy. Another serious problem with immigration into the U. S. is that much of it is illegal. Some illegal immigrants are involved in illicit activities, others join terrorist groups; many drain the economy of a state rather than contribute as they reproduce and obtain free health care and food and education. California today is an example of a state in tremendous debt chiefly because of so many illegal immigrants.