Colorado's "Mile High City," as Denver is known, provided something of a Wild West backdrop for conference participants, from cowboy boots to buffalo steaks. Colorado is pure Old West. Silver and gold mines -- mostly abandoned now except for tourists -- dot the nearby mountains. Denver, now a city of 2.1 million, was founded in 1858 after gold was found nearby and by 1890 was second in population only to San Francisco. When metals began to lose their economic lustre, Denverites turned to agriculture as a mainstay. Stockyards, canneries, flour mills and breweries made it a hub. Following World War II, oil and gas companies established regional or national headquarters in the city, fuelling a burst of growth and a dependence on fossil fuel revenues that backfired when gas and oil prices dropped and pushed the region into an economic depression in the 1980s. Colorado's western mind-set contributes to the state's maverick attitude, which in turn helps explain why Colorado became the first US state to impose a renewable energy standard via the ballot box. Voters demanded the state's utilities with more than 40,000 customers use renewable sources to produce 3% of their electricity by 2007, 6% by 2011 and 10% by 2015. Currently the state has 229 MW of wind power online and another 200 MW in the works.