Current laws require applicants for citizenship to have entered the country legally. That is pretty standard anywhere in the world where I have lived or worked.
The US also has visa programs for people who have enough money to start or invest in a business, and they can later apply for residency and citizenship.
It's more complicated than that: one of my daughters does nothing but apply for visas for refugees from Venezuela and Nicaragua and for work visas music industry people who are coming here for tours or to record in US studios.
Little known fact: Sharkira had some difficulty coming to the US to record her third album. Here first two were not successful in Colombia and the INS people thought she was trying to come to live in the US rather than to record.
She got the visa, recorded the album and it went triple platinum.
And I have a family member who came legally to to the US, learned English in High School, got a degree and applied for citizenship as soon as they were able.
Similarly, my first girlfriend in Ecuador had numbers tattooed on her arm. She and what remained of her family were granted special Holocaust survivor residency and then citizenship in Ecuador. They legally entered under a WW II refugee program.
