Founded in 1794, Thornhill stands as a testament to centuries of history and evolution. Its origins trace back to the northern bounds of the Ladies Golf Club on the east side of Yonge, extending further north on the west side, with the southern boundary encompassing John Street and Arnold Avenue/Elgin Street. The settlement's pioneers on Yonge Street were Asa Johnson and Nicholas Miller, the latter settling on the Markham side. Notably, the arrival of Benjamin Thorne in 1820 from Dorset, England, marked a pivotal moment. Thorne, an industrious figure, operated a gristmill, a sawmill, and a tannery, transforming the settlement into Thorne's Mills and later, Thorne's Hill, from which the current name derives. The untimely demise of Thorne in 1848, following a severe wheat market crash, echoes a chapter of the settlement's past.

 

Between 1830 and 1848, Thornhill experienced a period of robust growth and prosperity. A burgeoning business district emerged along its segment of Yonge Street, between Centre Street and John Street. Improved road conditions saw stagecoaches traversing between Holland Landing (Lake Simcoe) and York (Toronto). This era witnessed the construction of enduring churches that still grace Thornhill today.

 

The twentieth century marked Thornhill's sustained growth, owing much to its strategic location along Yonge Street, a pivotal transportation route. The advent of the electric radial Metropolitan line in 1898 facilitated unprecedented connectivity, enabling residents to reside in Thornhill and work in Toronto. The subsequent decades saw the automobile era further enhancing travel along Yonge Street.

 

In 1931, Thornhill attained the status of a "Police Village," establishing its political autonomy. The village, led by a reeve, thrived until 1971 when York Region was established, prompting municipal reorganization. Thornhill's administration returned to Markham and Vaughan, which attained Town status. Despite these changes, social institutions continued under Thornhill's administrative structure, maintaining a distinctive identity within the broader regional context.

 

Defined by the geographic boundaries of Dufferin Street to the west, Highway 7 to the north, Steeles Avenue to the south, and Highway 404 to the east, Thornhill evolved into a dynamic suburban hub since the 1960s and 1970s. The ongoing growth and development resonate with the patterns observed across the Greater Toronto Area, positioning Thornhill as an integral part of the region's urban narrative.