 In 1960, US 15 from the MD 26 interchange to Harmony Grove was expanded to a divided highway.The Frederick Freeway gained exit numbers in 1965, the same year the highway's interchange with 7th Street was added.The exit numbers ranged from 1 at the freeway's interchange with MD 144 east of Frederick to 9 at the highway's interchange with MD 26; the 7th Street interchange became exit 7A.