Economic regions and cities Since the days of early agricultural settlement, the majority of Alberta's population has been concentrated in the parkland belt (mixed forest-grassland), a boomerang-shaped strip of land extending along the North Saskatchewan River from Lloydminster to Edmonton and then along the Rocky Mountain foothills south to Calgary. This area is slightly more humid and treed than the drier prairie (grassland) region called Palliser's Triangle to its south, and large areas of the south (the "Special Areas") were depopulated during the droughts of the 1920s and 30s. The chernozem (black soil) of the parkland region is more agriculturally productive than the red and grey soils to the south. Urban development has also been most advanced in the parkland belt. Edmonton and Red Deer are parkland cities, while Calgary is on the parkland-prairie fringe. Lethbridge and Medicine Hat are prairie cities. Grande Prairie lies in the Peace River Country a parkland region (with isolated patches of prairie, hence the name) in the northwest isolated from the rest of the parkland by the forested Swan Hills. Fort McMurray is the only urbanized population centre in the boreal forest which covers much of the northern half of the province. Calgary and Edmonton The Calgary and Edmonton regions, by far the province's two largest metropolitan regions, account for the majority of the province's population. They are relatively close to each other by the standards of Western Canada and distant from other metropolitan regions such as Vancouver or Winnipeg. This has produced a history of political and economic rivalry and comparison but also economic integration that has created an urbanized corridor between the two cities. The economic profile of the two regions is slightly different. Both cities are mature service economies built on a base of resource extraction in their hinterlands. However, Calgary is predominant in hosting the regional and national headquarters of oil and gas exploration and drilling companies. Edmonton skews much more towards governments, universities and hospitals as large employers, while Edmonton's suburban fringes (e.g. Fort Saskatchewan, Nisku, Strathcona County (Refinery Row), Leduc, Beaumont, Acheson) are home to most of the province's manufacturing (much of it related to oil and gas). Calgary-Edmonton Corridor The Calgary-Edmonton Corridor is the most urbanized region in the province and one of the densest in Canada. Measured from north to south, the region covers a distance of roughly . In 2001, the population of the Calgary-Edmonton