Twin States: A Multiplier Effect

The Twin States study addresses an important, unanswered question in the field of women in politics. Are high-level elected women randomly distributed, or are there measurable factors driving their success in particular states? Data collected for this project conclusively shows that the current distribution of high-level women is not random. Certain states are more likely than others to elect women as governor or senator(s).

Find states with …

features correlated to electing more women

Women In Legislative Leadership
Same-Day Voter Registration
Female State Legislators
Female US Representatives
“Clean Elections”
High Education Levels
More Diversity

recent elections

2013 2014 2015 2016

Key Findings


Triplet States Three women elected as senator(s) and governor, serving concurrently or within two election cycles.

Twin States Two women elected as senators in the same state, or as governor and senator, or two governors within two election cycles.

Single States One woman elected as senator or governor.

Zero States No women elected as senator or governor.

Research Conducted By

Shauna Shames
PhD candidate, Harvard University
Lake Research Partners
Chesapeake Beach Consulting

States more likely to elect multiple high-level women (“twin states”) differ from other states:

  1. Demographic/geographic factors: They tend to be larger, comprised of younger, more educated, and more racially-diverse populations;
  2. Political factors: They tend to be more Democratic and have more women in their state legislative and Congressional delegations (especially in legislative leadership), same-day voter registration, public financing; and
  3. Electoral history: They often have already elected a woman to a top office.

As to the last, time-series modeling—which looks at this relationship over years – strongly suggests that having one woman in a top office leads to the election of other high-level women within that same state. (This relationship appears to hold even when controlling for incumbency; the finding is not due to the same top-level woman holding office in her state for a long period of time.)

The mechanisms driving the relationship between a first female high-level office-holder and the election of a second (or more) are not entirely clear. Prior research and experience suggest several potential mechanisms to be driving the linkage between multiple high-level women officeholders in the same state.

Read the Executive Summary


Strategies for Change & Next Steps

With campaigns for top political offices requiring increasingly large sums of money, both organizations and individuals are becoming more strategic with their resources. The twin states phenomenon provides an opportunity to target specific states with an increased likelihood of electing women to high-level offices.

Despite the relatively small number of states that have achieved twin status since 1992, the growing number of twins demonstrates a swifter route to political parity.

  1. There are concrete actions within states that may help facilitate the election of women to highest political office:
    • Electing more women to the state legislature and ensuring their inclusion in state legislative leadership positions.
    • Establishing same-day voter registration.
    • Enacting clean-elections/public financing laws.
  2. Where state characteristics are not changeable, in order to maximize the chances of electing female senators and governors, activists should be willing to consider non-traditional target states, with characteristics that include:
    • Higher levels of education;
    • A history of women serving in the state’s Congressional delegation; and
    • Greater racial and ethnic diversity.
  3. Support mentoring and networking within a state identified as a single or twin.
    • Candidates’ succession planning can play an integral role in building the bench and preparing the next wave of female candidates.
    • Experienced politicians (especially those holding Senate or governor’s seats) can provide guidance to their junior colleagues about committee assignments, relationship-building, and donor networks to facilitate future runs for highest-level office.
  4. Better prepare the pipeline.
    • Nearly half of all members of Congress served previously in their state legislature. Encouraging more women to run (and win) in races for lower-level office correlates significantly with becoming a single or twin state.

The twin states phenomenon provides an additional lens to view the movement to increase women’s representation in both governors’ mansions and the halls of Congress. While single states are a “good bet” for women as candidates for high office, other states with similar factors as single or twin states may also be ripe for shattering the glass ceiling.