101 Dundas Express and 201 Dundas are the rush hour express bus routes running on Dundas Street. Route 101 runs between Ridgeway Drive and Islington Subway Station via University of Toronto at Mississauga. Route 201 runs between South Common Centre and Islington.
Both routes provide a minimum 20 minute service frequency, synchronized to a combined 10 minute service east of Erindale where the routes are concurrent. Extra peak direction trips provide 5 to 8 minute service at the most congested times. Taking one of the express routes from Erindale to the subway saves 7 to 10 minutes compared to route 1 - Dundas.
Route 81 Dundas Express, as it was called then, was introduced in 1992, together with the HOV lanes on Dundas east of Dixie. Originally this was a peak direction only route, with most trips going onto or off of other routes at Islington; reverse-peak service was added later. In September 2005, the route was renumbered to 201 as part of a system-wide naming and numbering overhaul. By early 2008, the route was at its peak in terms of service provided, with frequencies of 6-8 minutes in the peak direction and 15-20 in the reverse peak direction.
In October 2009, express service on Dundas was split into two routes, the existing 201 and the new 101 Oakville Express, which at first extended as far west as the Uptown Core terminal at Dundas and Trafalgar. The trips were split fairly evenly between the routes, apart from morning westbound service, which was mostly transferred to the new 101.
In May 2011, the 101 was truncated to its current western terminus at Ridgeway due to low ridership on the Oakville section, and renamed the "Dundas Express". (The 202 had been renamed to just "Dundas" in 2010 to de-emphasize the express routes that didn't use blue buses.) The same shortened routing was used previously in 2010 from May to August.