Replying to your edit, H1 visa has been introduced by 1952 Immigration and Nationality Act, and in 1990 it was only split into H1A and H1B, to separate out nurs

Replying to your edit, H1 visa has been introduced by 1952 Immigration and Nationality Act, and in 1990 it was only split into H1A and H1B, to separate out nurses into H1A.