Gallup's analysis of political party affiliation at the state level in 2015 finds that 20 states are solidly Republican or leaning Republican, compared with 14 solidly Democratic or leaning Democratic states. The remaining 16 are competitive. This is the first time in Gallup's eight years of tracking partisanship by state that there have been more Republican than Democratic states. It also marks a dramatic shift from 2008, when Democratic strength nationally was its greatest in recent decades.
Importantly, even though Republicans claim a greater number of states, Democrats continue to hold an edge nationally in partisanship. In 2015 Gallup Daily tracking data, 43% of all U.S. adults identified as Democrats or leaned Democratic, compared with 40% identifying as Republican or leaning Republican. That is largely because many of the most populous states, including California, New York and Illinois, are Democratically aligned.