The economy of Alberta is the sum of all economic activity in Alberta, Canada's fourth largest province by population. Alberta's GDP in 2018 was CDN$338.2 billion. Although Alberta has a presence in many industries such as agriculture, forestry, education, tourism, finance, and manufacturing, the politics and culture of the province have been closely tied to the production of fossil energy since the 1940s. Alberta—with an estimated 1.4 billion cubic metres of unconventional oil resource in the bituminous oil sands—leads Canada as an oil producer.