Huge movements of population took place in Wales in the 19th century AD as new industries employed thousands of poverty-stricken agricultural labourers. Nonconformist chapels dominated the countryside and the new industrial towns, providing social life and encouraging a strict code of morality.

Nonconformity also encouraged educational reform, land reform and the disestablishment of the Church. A Government Commission of 1847, blaming poor educational standards on Nonconformism and the Welsh language, only radicalised more people. The 1880s saw a revival of interest in the Welsh language, and radical and liberal politicians called for the establishment of distinct national institutions. The concept of home rule for Wales first appeared.

At the beginning of the 20th century, conditions in Carmarthenshire’s factories and coalmines were hard. Workers joined trade unions and the new Labour Party to improve their lot. The Depression of the 1920s and 1930s brought unemployment and hardship, but after the War, in 1945, a Labour Government established the Welfare State. In the next 50 years, heavy industry declined and new mass media changed the traditional social life of south Wales, although provision of the Welsh language increased after 1970. In 1966, Gwynfor Evans was the first Welsh Nationalist MP elected for Carmarthen. Carmarthenshire elected its first Welsh Assembly members in 1999.