The A556 is a major road running through the middle of Cheshire from the A54 near Kelsall to the A56 and M56 south of Altrincham. Historically the main route between Chester and Manchester, it has been largely superceded by the M56 motorway to the north, apart from the section between M6 junction 19 and M56 junction 7. The M6/M56 junction is not full access, and so Manchester-bound traffic heading north on the M6 must use a 4-mile 4-lane single-carriageway section of A556 to reach the M56 (and vice versa). A dual-carriageway bypass of this section has been planned.
Apart from the Northwich bypass, most of the route follows the old Roman road between Manchester and Chester. The Northwich bypass was built in the late 1950s, although the central section, including the famous blue bridge over the River Weaver, was constructed in the late 1930s.