In the 2016 census, the town of Alliston grew by 25% since 2011 to 19,243 residents making it one of the top 10 fastest growing communities in Canada.

[citation needed] Alliston traces its history to three brothers, William, John and Dickson Fletcher.

In early November they built a cabin on the property, and the rest of the family joined them in April the next year.

This venture came to nothing, but the organization set up to investigate it later turned to the Hamilton and North-Western Railway to build a new arm from Clarkstown (now Beeton) through Alliston to Collingwood.

On May 8 the same year a fire started in the stables of the Queen's Hotel, and was quickly spread by high winds.

Collingwood was telegraphed for assistance and sent their fire engine by train, but the downtown area was gutted long before it could arrive.

This led to the creation of a waterworks the next year, which included twenty fire hydrants, and the addition of a hook and ladder truck in 1894.

Major residential areas are located to the north (as Previn Court Homes) and to the south, with additional residential and commercial developments made since then in the northwest (as "Alliston West"), north and southwest since the mid-1990s, with future developments expected in the future that could raise the population from 17,000 to 20,000.

The CPR (Toronto - Parry Sound - Sudbury) runs right up through the middle of town with a siding for Honda vehicles.

Earl Rowe Provincial Park is located three kilometers west of Alliston, in the amalgamated Township of Adjala-Tosorontio.

[4] Former mayor of New Tecumseth is Rick Milne The Member of Provincial Parliament for Simcoe—Grey is Jim Wilson, who was first elected in 1999.

This fully accredited hospital serves a catchment area that includes Adjala-Tosorontio, Canadian Forces Base Borden, Essa, Innisfil and New Tecumseth.