From 2004 to 2014, the percentage of people who identified themselves as Independents increased while the percentages of Republicans and Democrats decreased. After 2014, the percentages have been relatively stable. There are many reasons suggested for these trends.
(Note: Data was obtained from surveys conducted by Gallup. Lines represent 30-day moving averages.)
Gallup also asked survey participants who identified as Independents whether they leaned towards either the Republican or Democratic party. The trends for party registrants and those leaning towards the party are different than for the registered voters alone.
Since about 2016, the percentages of party registrants and leaners has increased for both parties. The percentage of “true independents,” people who do not favor either party, has decreased. This may be attributable to the increasing divide in the policies and rhetoric of the parties.