Situated at the foot of the Cedarberg Range where Jan Dissels River flows into the broad Olifants River. Clanwilliam formerly Jan Disselvlei (named after Jan Dissel, a botanist who lived 'at the Rhenosterbosch along the Piquetberg Mountains'), celebrated its 150th Anniversary in September 1964. The District originally formed part of the district of Stellenbosch. On 1 Feb. 1808 the Earl of Caledon, Governor of the Cape Colony from 1807-11; annexed that part of the District lying North of the Berg River to the new District of Tulbagh, at the same time declaring it a; 'sub-drostdy'. Daniel Johannes van Ryneveld was proclaimed as the assistant Magistrate. On 21 Jan. 1814 Caledon's successor, Sir John Cradock (1811-14), renamed the sub-magistracy after his father-in-law, the Earl of Clanwilliam. In 1820 efforts were made to settle four groups of Irish settlers under William Parker along the Jan Dissels River, but with little success. In 1822 the magistracy of Tulbagh was moved to Worcester, but on 1 Jan. 1837 Clanwilliam was separated from Worcester and proclaimed a District. In 1901 the Village of Clanwilliam became a Municipality, the first mayor being Charles Fryer, an Irish descendant of the 1820 Settlers. Water is obtained from the Jan Dissels River and electricity supplied by a hydro-electric plant below the Clanwilliam Dam in the Olifants River was completed in 1935.

This picturesque Town has a Saw Mill and a 'Veldskoen' Factory. It is the headquarters of the Rooibos Tea Control Board. A memorial Library in honour of Dr. C. Louis Leipoldt, (who was a South African doctor, journalist, and a leading poet of the Second Afrikaans Language Movement). Spent his childhood at Clanwilliam and his Grave-site is found in Clanwilliam, buried in a Cave in the Pakhuis Pass. During October of each year a popular regatta is organised on the Clanwilliam Dam in the Olifants River.
On account of high precipitation in the Mountains, the District is well watered by many perennial Streams. The Olifants River is dammed for irrigation purposes at Clanwilliam and Bulshoek. Clanwilliam is famous for its rooibos tea and oranges. 

-32° 11' 46.0172", 18° 54' 10.8"
New Dictionary of South African Place Names by Peter E. Raper