The A4213 was a short lived number for the B road across the north of Carmarthen. Originally the B4207, it was upgraded in the late 1960s to become the A4213, before being downgraded once more as an extension of the B4312 after the Carmarthen Bypass was built.
The road started on the A40 (now B4312) Picton Terrace, only a short distance away from the western end of the A4116, and headed northeast along St Catherine Street. It passed to the north of the town centre unlike the present road which passes through a shopping centre. After following Barn Road it bore left onto Francis Terrace and then right onto Old Oak Lane. The road ended back on the A40 (now A484).