Ammanford took its current name on 20 November 1880. The community that existed then and now known as Ammanford dates back to around the early 19th century. At that time the main highways went through the area, not to it. The north–south road from Llandeilo and Llandybie went to Betws, and the east–west road from the Amman Valley went to Penybanc and Tycroes, and further afield, both converging at a crossroads (now Ammanford Square). This in turn led to the development of coaching inns or staging inns and taverns catering for the needs of the traveller. The area eventually became identified by the name of one of these hostelries – Cross Inn.

The community of Cross Inn centred on the activity of the cross road, along with a small group of low-grade cottages sited in the vicinity of Carregaman Isaf which became known as Pentrefacas. Betws was a larger hamlet with the parish church, St David’s, as its focal point. All the area to the west of the River Amman fell within the parish of Llandybie.