I think, from some books I read at the library, that she's an American wedge-faced shorthair, but I have no idea if that method of determining cat breed is even still viable. (The book was written in the '50s.)
To me she looks like an American Shorthair. Of curse, since people have allowed their pedigree cats out roaming, their strains have been woven into what has become known as the Alley Cat.
I had been breeding Oriental Shorthairs for a number of years and was able to keep the line pure - that is, until I changed residences. Then all hell broke loose. Instead of coming into season only once a year (usually late December) they were giving birth in September and ignoring them. I found the dead newborns everywhere as they had just been dropped and abandoned. After five to six years, it seems that the line is coming through true to form.