DES MOINES — The last time Iowa had a race for governor without an elected incumbent, the Democratic candidate won 62 counties and the blue counties dotted the map from river to river. In this week’s midterm elections, even though the Democratic candidate lost by just 3 points, only 11 counties were blue, and they were all in central or eastern Iowa. The divide between rural and urban voters in Iowa continues to sharpen. Democrats dominate in the state’s biggest cities, while Republicans own the rural areas. It's existed for more than a few election cycles, but the contrast has...