Arnprior—often known as “The Prior”—is strategically situated at the confluence of the Ottawa and Madawaska Rivers. It originated in the early 1820s when Archibald McNab acquired a 1,200-acre grant, laying the foundation for what became McNab Township. Named in 1831 after McNab’s Scottish hometown, Arnprior’s early European-era settlement was firmly tied to the Ottawa Valley’s lumber boom.

In 1851, sawmilling magnate Daniel McLachlin established a major sawmill harnessing the Madawaska’s flow, connecting the mill’s operation to McLachlin’s wider influence in regional infrastructure development—bridges, roads, and economic growth catalysts. Arnprior was incorporated as a village in 1862 and elevated to town status in 1892, reaching 8,114 residents by 2011.

Rail developments—Canada Central Railway in 1864 and standard-gauge Canadian Pacific lines in 1880—shaped land parcel layout by imposing railway easements and defining industrial corridors . This transport infrastructure left a lasting imprint on cadastral boundaries and property deeds.

Architectural and cadastral heritage is visible today in the downtown Heritage Conservation District and historical structures such as the O’Brien Theatre (circa 1919) and former sandstone post office—now the Arnprior & District Museum.

Surveyor’s view: Arnprior stands as a textbook study in layered cadastral development: Crown-granted township surveying; rugged lot and concession layouts shaped by watercourses; mid‑19th-century industrial infrastructure; and rail corridors slicing through land blocks. Today’s parcel boundaries remain deeply rooted in these foundational grids, waterways, and transportation alignments—providing a clear narrative for OLS professionals tracing property lines, easements, and historical rights-of-way.