In the early 1990s, the population of Bend, Ore., was around 25,000 and leaned Republican. A lumber mill operated along the banks of the Deschutes River in Oregon’s high-desert country. Today, the lumber mill is an REI outdoor recreation store. The population has quadrupled. And for the first time in memory, the number of registered Democrats in Deschutes County recently eclipsed the number of Republicans.