Melting pot works best if people look alike and speak the same language. Whites look alike and — within a couple of generations — spoke just English. Melting pot accomplished.
Immigrants tend to be non whites and they speak their own language, for the most part. The first one is very hard to break and the language thing is not going to happen with proud Hispanic mestizos speaking their colonial masters’ Spanish language as a matter of pride.
It became a tossed salad, not a Melting Pot.
In other words, we’re becoming The Balkans.
Earlier immigrants learned English within a generation, because they were given no choice. Schools taught in English, period. You had to speak English to be hired in businesses outside your ethnic ghettos. And you HAD to get a job, or starve.
Eliminate welfare, and eliminate requirements to accommodate Spanish in business and government, and they WILL learn English