New Hampshire has become a competitive swing state in presidential elections over the past two decades. Though New Hampshire was once a reliable red state and the home for many “Yankee Republicans,” the state has experienced a shift toward the Democratic Party beginning in the early 1990s. Scholars often attribute this shift to the “migration theory,” arguing that the influx of Massachusetts liberals who migrated to New Hampshire in the latter half of the twentieth century has created a larger Democratic voting bloc in the state. However, a county-level analysis of New Hampshire provides a different story. Southern urban counties with the highest migration rates, such as Hillsborough and Rockingham, had relatively small gains of Democratic voters and remain competitive swing counties. Northern rural counties with much lower migration rates, such as Coos and Grafton, have experienced a far greater political shift to the left. By using both of these case studies, this report casts doubt on the “migration theory” by showing that numerical migration rates do not fully account for New Hampshire’s shift. Instead, this report finds that the different types of economies in the southern and northern parts of New Hampshire significantly influence the political effects of migration in the state, offering a more nuanced theory based on county-level data than the one currently provided for the state as a whole