The following various sections of public roads shall, respectively, be adopted by the Commonwealth as a State highway, to be constructed and maintained at the expense of the Commonwealth under the provisions of present or future laws governing State highways, except as hereinafter provided:

Beginning at a point in the city of Pittsburgh, at the south end of the Point Bridge on Carson Street, west; thence along Carson Street, west, to Smithfield Street; thence along Carson Street, east, to the line between the city of Pittsburgh and Baldwin Township; thence over a section of improved county road in Baldwin Township, known as the Carson Street East Extension, to the line between Baldwin Township and the city of Pittsburgh; thence over Baldwin Road to an intersection with Riverton Street; thence along Riverton Street to an intersection with Mifflin Street, which is a continuation of the Glenwood Bridge,--a distance of about 6.1 miles.