A possible explanation for the rise of the incumbency advantage in U.S. elections asserts that party and incumbency are close informational substitutes. A common claim in the literature is that, as the salience of partisan cues decreased, voters attached themselves to the next available piece of information – incumbency. Minnesota state legislative elections provide a unique setting for testing this idea. These elections switched from using non-partisan to partisan ballots and primaries in 1973. We find that, after the switch to partisan elections, party voting increased substantially. However, contrary to expectations, the incumbency advantage also increased. These patterns suggest that party and incumbency are not close substitutes for large numbers of voters, and that cue-substitution cannot explain the rise of the incumbency advantage.