Basic Facts About Hastings County. Population: 125,915; Size: 5,964 square kilometres; Length: 160 kilometres, north-south, Width: 45-55 kilometres, variable; Relative Size: Second largest county in Ontario, after Renfrew; Geographic Centre: Community of McDonalds, Tudor Township; Altitude: 75 metres (245 feet) above mean sea level at Belleville Harbour, 488 metres (1,600 feet) atop hills near Algonquin Park; Population Centres: Bancroft, Belleville, Deseronto, Madoc, Marmora, Quinte West, Stirling, Tweed