Waterloo is a city in Southern Ontario, Canada. It is the smallest of the three cities in the Regional Municipality of Waterloo, and is adjacent to the city of Kitchener. Kitchener and Waterloo are often jointly referred to as "Kitchener-Waterloo", "KW", or "the Tri-City" (to include the City of Cambridge), although they have separate city governments. There have been several attempts to amalgamate the two cities (sometimes with the city of Cambridge as well), but none have been successful. At the time of the 2011 census, Waterloo had a population of 207,438. As of Apr 30 2015, Waterloo has a population of approximately 283,500.