Slough is a town in Berkshire, England, in the Thames Valley 20 miles west of central London and 19 miles north-east of Reading, at the intersection of the M4, M40 and M25 motorways. It is part of the historic county of Buckinghamshire. In 2020, the built-up area subdivision had an estimated population of 164,793. In 2011, the district had a population of 140,713. Slough borders Greater London and Buckinghamshire.