A new Gallup poll finds 42% of Americans, on average, identified as political independents in 2013, the highest measured in 25 years. Meanwhile, Republican identification fell to 25%, the lowest over that time span. At 31%, Democratic identification is unchanged from the last four years but down from 36% in 2008.

The percentage of Americans identifying as independents grew over the course of 2013, surging to 46% in the fourth quarter. That coincided with the partial government shutdown in October and the problematic rollout of major provisions of the healthcare law, commonly known as "Obamacare."

Image from: Gallup

Democrats maintain their six-point edge in party identification when independents' "partisan leanings" are taken into account. In addition to the 31% of Americans who identify as Democrats, another 16% initially say they are independents but when probed say they lean to the Democratic Party. An equivalent percentage, 16%, say they are independent but lean to the Republican Party, on top of the 25% of Americans identifying as Republicans. All told, then, 47% of Americans identify as Democrats or lean to the Democratic Party, and 41% identify as Republicans or lean to the Republican Party.

Image from: Gallup

The rise in political independence is likely an outgrowth of Americans' record or near-record negative views of the two major U.S. parties, of Congress, and their low level of trust in government in general.