This "wait list" is created by the law. Congress has set the number of immigrant visas ("green cards") to be issued each year. Since there are more people than

This "wait list" is created by the law. Congress has set the number of immigrant visas ("green cards") to be issued each year. Since there are more people than visas available - some people are not getting them and, thus, do not become immigrants. It's not some kind of bureaucratic snafu with the paperwork stuck in some desk somewhere - this is by law. So they would be immigrants only if the law was different somehow.