Great question; I've always wondered about other states, but here's mine:
I'm a resident of New Hampshire, so it's not necessarily representative of the larger states. We've got nothing like that for individual instruments instruction. Piano and strings might be the exception, but I don't consider any of the methods ubiquitous or even regularly agreed upon.
The closest thing we've got is the NYSSMA (New York State School Music Association) manual, which defines solo pieces into six grades for each instrument. However I take exception to many of their grading choices, and newer pieces are not regularly assimilated into the lists. Many Northeast all-state, etc. festivals use these grades.
Music colleges, especially music education programs, have WIDELY varying criteria, which at smaller schools can even vary by instrument and year. There are some college music programs that have students with abilities I've seen in high schoolers. (That doesn't address their teaching ability, though.) Unfortunately, I've seen some college students who would have had a call to the parents about taking the horn home, if they were in a high school band of mine!
On the other hand, larger schools, especially in or near larger cities, may be auditioning hundreds of people, and can afford to be quite selective, even for non-performance majors.
As for the United States not having a ubiquitous graded system like that; I think it has a lot to do with the musical culture here. Unfortunately, as shown by so many schools cutting music; there is very little emphasis on music and the performing arts in general. Most students receive very little music class after elementary school, if at all, and many school schedules make it difficult for students to take regular performing art courses. Even in the elementary grades, students receive very little classroom time in music class, sometimes only a half hour per week. They get as far as screeching on recorders, and then move on to middle school.
In europe (and it could be an outsider's "grass-is-greener" effect) it seems that music and art are more densely woven into the culture, and therefore the school system.
I'll be interested to see whether residents of other states have any widely-used systems!