In 1821 Jasper Martin from Newcastle England built a grist mill along the banks of the Sixteen Mile Creek, near today's Milton, founding a settlement of 60 people first called "Martin's Mills" which had an ashery, small store and a post office. In 1837, with a population of over 100 people, the community was renamed Milton, for the English poet John Milton, who wrote the memorable poem, Paradise Lost. The closeness to the Escarpment provided building materials used in the early town'sconstruction.
Oakville was founded in 1827 by Colonel William Chisholm (1788-1842), who became a merchant and shipbuilder on 960 acres granted at the mouth of Sixteen Mile Creek, where he soon established the first privately owned harbour in Upper Canada and handled trade between Hamilton, Toronto and in 1934, the US with William Chisholm serving as the first Customs Inspector. When the town was incorporated in 1857, George King Chisholm became Oakville's first mayor.
In the early days of Burlington, animal farming and fruit growing were prominent activities and contributed towards its rapid growth. In 1873, the adjacent hamlets of Wellington Square and Port Nelson amalgamated into the village of Burlington.
Halton's largest industries included wood processing, fishing, leather production, mineral extraction and paper production. The area was also important in "stone-hooking" where shale and granite was raked from the bottom of Lake Ontario for use in roads and buildings.
When the railway reached Milton in 1877, the town grew with several brickyards by the escarpment around Milton Heights. Most famous was the Milton Pressed Brick Company, and several buildings in today's downtown Milton were made with bricks that bear either the MPB or Milton stamp. The railway also opened up the quarry industry which manufactured cut limestone used in area buildings, including the Town Hall.
In 1853, Halton became a separate county with its own governing council headed by a warden, and comprised of Nelson, Trafalgar, Esquesing, and Nassagaweya Townships, with Milton being the County Seat. In 1888, the Barber paper mill on the Credit River in Georgetown, became the first factory in Ontario to use long distance transmission of hydro-electric power.