There should be employment agencies at the border. From here, employers across the US can look for workers who will be vetted by the US government. There could be a couple types of work visas:
- Work only: authorized to work the US with intention of going back to their home country
- Work / Citizenship visa: authorized to work in the US AND starting the path to citizenship. Once granted, this work/citizenship visa would put the person on the path to citizenship. After 1 year of working, and ONLY IF there are no legal issues (drunk driving offenses, felonies, etc) they would become a Legal Resident. After another year of working, paying taxes, buying property, etc, they would be granted citizenship ONLY IF, during the two years of waiting, they had no felonies, bankruptcies, or any major legal issues. This vets them as good neighbors and citizens at the same time we allow good workers to move into our country and contribute.