Beginning operation in 1861, the Yonge streetcar line was the first streetcar line in Toronto and the first in Canada. It started off as a horsecar line and closed in 1954 operating two-unit trains of Peter Witt motors pulling a trailer. Under the Toronto Transportation Commission, the Yonge line was the busiest and most congested streetcar line in the city leading to its replacement in 1954 by the Yonge Subway line, also Toronto's first and the first in Canada.