arrived immigrants. These became some of Toronto's first ethnically-based neighbourhoods. The working class Irish who laboured in many of the factories were concentrated in the eastern part of the city, and these neighbourhoods were named Cabbagetown and Corktown after them. Jewish immigrants also began arriving in considerable numbers at the end of the 19th century, and they settled in a region that was known as The Ward, centred at the corner of Bay Street and a collection of side streets that would later become Dundas Street. In the early 20th century, Chinatown would develop into another important neighbourhood just to the east. Middle and upper class residents left the core and moved into new areas further out, creating a number of new neighbourhoods. A ring of former farmland around the city was thus developed into new residential areas. These included The Annex, named for its annexation to the city of Toronto, and the former village of Yorkville. This process accelerated considerably at the end of the century with the introduction of the streetcar. The streetcar allowed residents living outside the central business district to travel to work with ease. New areas, again mostly middle and upper class, grew up along the streetcar lines creating new neighbourhoods like Riverdale, The Beaches, Birch Cliff, North Toronto, and Parkdale. Working class streetcar suburbs developed in New Toronto, Mimico and Long Branch in what is now Etobicoke. Postal districts By the 1920s, most of the neighbourhoods of old Toronto had been established. In a non-comprehensive list a 1925 writer to the Toronto Star listed Rosedale, Riverdale, Parkdale High Park, Junction, Danforth, Earlscourt, Wychwood, Willowvale, North Toronto, Beach, and Leaside. All of these neighbourhoods are still commonly used today, with the exception of Willowvale, which is now known as Christie Pits, the name of the park it surrounds having been changed the same way. In 1925, the Post Office divided Toronto into ten postal zones (see map), in an effort to facilitated mail sorting in an era before postal codes. There was no obligation to use the zone numbers, and were originally not widely adopted. After the Second World War, the zone numbers did begin to be used extensively. The postal districts became one of the primary ways of dividing up the city. Residents frequently described themselves as living in Toronto 2 or Toronto 10. The system was retained until 1971, with gradual modification. New