How many states have a split congressional delegation between Democrats and Republicans?

1. A clear headline — How analysts reached the “31 states” conclusion

The strongest analytic claim comes from a Smart Politics compilation that reports 19 state delegations are single-party—12 all-Republican and 7 all-Democratic—leaving 31 states with mixed delegations where at least one senator or representative is from a different party than another member of the state’s congressional delegation ^[1]. That calculation is simple arithmetic: 50 total states minus 19 single-party delegations equals 31 split-delegation states. The source frames this as part of a larger trend analysis about the number of single-party delegations reaching a high, which implicitly produces the complementary count of split delegations ^[1]. This is the only source among the supplied analyses that directly supplies a numeric conclusion for split delegations.

2. What supporting material exists and what it does not say

Ballotpedia and other included analyses provide contextual data about changes in congressional delegations across recent Congresses but do not directly state a current count of split-state delegations ^{[2] [3]}. One Ballotpedia analysis focuses on comparisons between the 117th and 118th Congresses and on the percentage of new members without explicitly enumerating split delegations ^[2]. Another Ballotpedia item concerns politically split Senate delegations in a small number of states but addresses only the Senate, not full congressional delegations that combine Senate and House membership ^{[3] [4]}. These gaps highlight that the numeric claim rests principally on the Smart Politics synthesis ^[1].

3. Why the Senate-only analyses are relevant but incomplete

Analyses that track split Senate delegations identify only a handful of states with one senator of each party, notably mentioning a record-low number for split Senate delegations in the 119th Congress ^[4]. That observation is useful context because it shows Senate homogeneity has grown, but it does not translate directly into the number of split statewide congressional delegations (which include both senators and all House members). Using Senate-only counts to infer full delegation splits risks understating or overstating splits because a state could have two senators from one party but a mixed House delegation, or vice versa ^[4]. The supplied analyses therefore require the Smart Politics aggregation to answer the original question.

4. Points of caution: methodology, timing, and implicit assumptions

The Smart Politics count that yields 31 split states is presented as an inference from a tally of single-party delegations rather than as a standalone enumeration of split delegations ^[1]. This approach assumes the underlying roster of senators and representatives used in that tally is current and correctly classified by party. The Ballotpedia materials in the packet offer election-comparison context but do not validate the Smart Politics snapshot directly ^{[2] [3]}. Because the provided documents vary in scope—some focused on Senate splits, some on Congress-wide composition—the conclusion depends on the assumption that the Smart Politics dataset accurately reflects the same temporal snapshot as the other materials ^[1].

5. Bottom line and alternative interpretations readers should consider

Based on the supplied analyses, the best-supported answer is that 31 states have split congressional delegations, derived from Smart Politics’ report that 19 states have entirely single-party delegations and the remainder are mixed ^[1]. Alternative interpretations could emerge if one relied solely on Senate-focused reports—which record far fewer split delegations—or if different snapshots of membership were used, since special elections, party switches, or midterm changes can alter delegation composition between congressional sessions ^{[4] [2]}. Readers should treat the 31-state figure as a snapshot conclusion anchored in the provided Smart Politics analysis and cross-check it against up-to-date member rosters for any real-time changes ^{[1] [2]}.