In 1901, the American-owned Niagara, St. Catherines & Toronto Railway  established the Niagara, St. Catherines & Toronto Navigation Company following the purchase of the Lakeside Navigation Company. Through Lakeside Navigation the new navigation company obtained its first two steamships, the 348-ton Lakeside and the 637-ton Garden City .They allowed the company to move into the Toronto market, providing tourists for the amusement park and passengers for the railway many of whom were no doubt bound for Niagara Falls. 
          Meanwhile, back in the United States, the company's owners were fighting for control of their American lines and were forced to sell the Niagara, St. Catherinels & Toronto in 1907 to raise capital. They sold to William Mackenzie and Donald Mann, owners of the Canadian Northern Railway. The new owners of the Niagara, St. Catherines & Toronto Railway and its steamship subsidiary immediately embarked on an expansion program aimed at the establishment of a new line from St. Catherines to Port Colborne. With the new line, the railway hoped to capture a portion of the passenger and freight traffic between Lakes Ontario and Erie, which had been controlled for so long by the Grand Trunk and earlier by the Welland Railway. The extension was opened to traffic in 1911. In 1913 a line was built from St. Catherines to Niagara-on-the-Lake.
          By 1911 passenger traffic on Lake Ontario had increased so much that the small Lakeside was hardly able to keep up with demand. She was replaced by the 1,256-ton Dalhousie City, launched earlier that year by Collingwood Shipbuilding. Well equipped to handle the route to Toronto, Dalhousie City was even able to take over the duties of the Garden City in 1916. When the Canadian Northern fell into financial despair during the First World War, the Canadian government had no choice other than to take over  the assets of the railway in 1917, including the Niagara, St. Catherines & Toronto Railway and Navigation Companies, and in 1923 they came under the control of the newly formed Crown Corporation, Canadian National Railways. 

           Government backing brought with it many advantages for the companies. During the post-war period, passenger traffic experienced an upturn and for the Niagara, St. Catherines & Toronto Navigation Company, the volumes were too great for the Dalhousie City to handle alone. Fortunately the steamship Northumberland, which since 1894 had provided a ferry service for the government across the Northumberland Strait between Prince Edward Island and the mainland, had become surplus and in 1920 was transferred to the navigation company for duty on Lake Ontario. While ownership of the 1,255-ton, British-built Northumberland remained with the federal government through the Minister of Transport, she was in all other respects a part of the navigation company's fleet.
          For the next three decades the Dalhousie City and the Northumberland carried thousands of excursionists between Toronto and Port Dalhousie, keeping the interurban line supplied with passengers and Canadian National supplied with needed revenue. 

Niagara, St. Catherine's and Toronto Navigation Co.