Ashton upon Mersey lies within the historic county boundaries of Cheshire, and became part of Greater Manchester in 1974.

However, this was based on the De Situ Britanniae, a manuscript forged by Charles Bertram, and there is no evidence to suggest any such station existed.

[5] The first building of St Martin's Church dated from 1304, but a chantry on the same site is believed to have existed since the 9th century.

There is one main tier of local government covering Ashton upon Mersey, at metropolitan borough level: Trafford Council.

In 1866, the legal definition of 'parish' was changed to be the areas used for administering the poor laws, and so the Sale and Ashton upon Mersey townships (the latter including the detached parts from Bowdon) became separate civil parishes.