Midterm and presidential election years both include congressional contests. The main difference is that a regular presidential election selects a president, while the midterms occur between those presidential elections.
House terms last two years; Senate terms are staggered across cycles. That structure means congressional representation can change while the president remains in office. Source: USAGov.
The ballot changes, not just the headline
In a presidential year, attention often concentrates on the race for the White House. In a midterm year, congressional, gubernatorial, legislative, and local contests may play a larger role in coverage.
The exact ballot still depends on location. “Midterm election” does not mean every state elects a governor or every Senate seat is contested.
For a voter, a sample ballot is more useful than a national list of prominent contests.
Why turnout comparisons require care
A past presidential electorate should not simply be copied into a midterm forecast. Participation can vary by election type, campaign, competitiveness, and local issues.
To assess a claim about turnout, ask whether it uses eligible citizens, registered voters, ballots cast, or some other denominator. Two percentages with different denominators are not directly interchangeable.
Historical patterns provide context. They do not identify which individuals will participate in a future election.
Political interpretation
Midterms can indicate voter reactions to an administration, but congressional elections also involve local candidates and circumstances. A national swing can coexist with district-level exceptions.
Suppose an incumbent wins despite a difficult national environment for their party. Possible explanations include their record, the challenger, or the district's electorate. Establishing which explanation matters requires evidence beyond the result itself.
How to compare years responsibly
Use the same office, comparable geographic boundaries, and clearly defined turnout measures. Redistricting can make a direct House comparison less straightforward because a district number may refer to a different set of voters.
Read both national totals and local results. One describes the broad environment; the other identifies who will actually represent each constituency.
Related reading: competitive House districts and likely voter polls.