We pretend that "immigration" Is among the enumerated powers of the federal government but initially it wasn't. Take a look at what the constitution said about "importing such persons' before 1828 ~
You probably imagine the United States was a very popular place for folks to emigrate to in the early 1800s ~ but it wasn't. You had to be rather desperate to want to come here. The sea voyage was very dangerous and most of our great cities had not yet been cleared of the malarial swamps that killed people by the thousands every year.
A climate disaster in Europe that occurred repeatedly throughout the 1800s made America very popular ~ when the choice was death by starvation or a voyage to Baltimore or Halifax.
That was also before such folks qualified for welfare, etc.
The real problem isn’t the legal immigration, it’s the handouts. Get rid of the handouts and you’ll see the productive come to America.