It would be premature to label Colorado’s Fourth District one of the nation’s swing districts, but that could change as a result of the 2012 election season. A court will decide the new outline of the district next month but the district is undergoing a more profound transition. It is becoming the thing Iowa is supposed to be: A moderately conservative middle-American political testing ground, where unaffiliated independents make up roughly a third of the voters, where the aging still-mostly-white population is increasingly ethnically mixed and where high-tech and R&D industries are replacing manufacturing and farming as the main drivers of the economy.