The following various sections of public roads shall respectively be adopted by the Commonwealth as State highways, to be constructed and maintained at the expense of the Commonwealth under the provisions of present or future laws governing main State highways, that is to say:
Six hundred and forty-nine. Beginning at the Marietta Borough-East Donegal Township Line, and extending in a northerly direction to Mt. Joy Borough, and intersecting with State highway route number one hundred and twenty-nine.
36 P.S. § 1625