ASHTON-UNDER-LYNE, municipal and parliamentary borough, Lancashire, England, on the river Tame, a tributary of the Mersey, 62m. E. of Manchester. Population (1891) 40,486; 51,573. It is served by the London Midland and Southern and London and North-eastern lines. The derivation from the Saxon aesc (ash) and tun (an enclosed place) accounts for the earliest orthography, Estun. The addition subter lineam is found in ancient deeds because the place is below the line or boundary of Cheshire, which once formed the frontier between North umbria and Mercia. The manor was granted to Roger de Poictou by William I., but before the end of his reign came to the Greslets as part of the barony of Manchester. The lord of the manor still holds the ancient court-leet and court-baron half-yearly. A church or chapel is mentioned here in 1261-62, but the present church of St. Michael is almost entirely modern. One of the markets dates back to 1436. The ancient industry was woollen, but soon after the invention of the spinning frame the cotton trade was introduced, and as early as 1769 the weaving of cotton yarn by machinery soon became the staple industry, and has remained so. Hat-making and iron-founding and machinery works are also important, and there are large collieries in the neighbourhood.
Stamford Park, presented by Lord Stamford, is shared by the towns of Ashton and Stalybridge. The town has a technical school, a school of art and free library. Ashton-under-Lyne had long enjoyed the name of borough, but it was not until 1847 that a charter of incorporation was granted. The parliamentary bor ough, which includes the urban district of Hurst, returns one member. Area of municipal borough, 1,345 acres.