|Distance:||5.1 miles (8.2 km)|
|Meets:||Unclassified M4, A48, A483, A4118, B4603, B4290, A4067|
|Route outline (key)|
The B4489 runs south from Junction 46 of the M4 at Llangyfelach to Swansea city centre. A recent addition (not reflected in all mapping) has been a 1.2-km northward extension to the Park and Ride facility on the site of the former Felindre tinplate works.
South of Llangyfelach the road traverses the north Swansea suburbs of Tirdeunaw, Tre-boeth, and Brynhyfryd (all former mining and metal-working districts, now chiefly residential in character) before reaching the northern edge of the city centre at the busy, and often congested, light-controlled Greenhill junction, known locally as "the Dyfatty lights", where the A83, A4118, B4489, and B4603 all meet.
From here, the route runs along High Street, past the railway station and the remains of the castle, then down Wind Street (once the heart of Swansea's financial district, now chief home of the city's "night-life culture" and therefore closed to traffic in the evenings), terminating where it meets the A4067 Victoria Road / Quay Parade.
The B4489 was not part of the original 1922 numbering scheme, but was appearing on maps by 1932 – originating on the A48 at Llangyfelach and terminating on the then-B4290 close to the now-disappeared Victoria railway station in Swansea. The route through Swansea town south of the Greenhill / Dyfatty crossroads followed a more westerly course, however, than that taken by today's B4489 (High Street and Wind Street, which used to be the A483), instead running along Dyfatty Street, Orchard Street, Waterloo Street, Church Street, and Rutland Street.