What would happen to Congress if Washington, DC became the 51st state?

For years, the official motto of the District of Columbia has been “Taxation without representation.”

The residents of Washington, D.C. do not have representation in the U.S. House or in the Senate. People who live in the district, on average, pay higher federal and local taxes, but they have no say about how their tax dollars are spent, and no vote on issues such as health care, Social Security and foreign policy.

As a sociologist researching demographic and political behavior, I do not think that this is fair.

The next U.S. flag? Milan Suvajac/Wikimedia, CC BY-SA
On May 29, the House Majority Leader Rep. Steny Hoyer announced in an op-ed in The Washington Post that he will co-sponsor a bill with Delegate Eleanor Holmes Norton, the nonvoting member of the U.S. House from the district, to make the nation’s capital the 51st state of the U.S.

If the district becomes the 51st state, its residents would finally have representation.

How the district sizes up

“Defending the new Constitution, James Madison assured his fellow Americans that residents of this new capital district would happily live there ‘as they will have had their voice in the election of the government which is to exercise authority over them,’” wrote Hoyer in his op-ed. “But for 228 years, our government has denied them that voice.”

Statehood for the district has been opposed by Republicans in the past, mainly because the district is heavily Democratic.

About 76% of the registered voters in the district are Democrats, while just 6% are Republicans. Most of the others have no party affiliation, though a few are Libertarians or Green Party members.

This occurs even though, with over 700,000 residents, the district is larger in population than two states: Vermont and Wyoming. Two other states have just a few more residents than the district, Alaska with 737,000 people and North Dakota with 760,000.

But those four states each have one representative in the U.S. House and two senators. Washington, D.C. has neither a representative nor any senators.

Changing the political math

What will happen politically if the district becomes the 51st state? How will the distribution of representatives and senators among the states change?

The answers show why Republicans consistently vote against statehood for the district.

Every state has two senators. Currently, the Senate has 45 Democrats, plus two independent senators who caucus with the Democrats. There are 53 Republicans in the Senate.

If Washington, D.C. is granted statehood, its two senators will almost certainly be Democrats, giving the Democrats 49 out of the now 102 seats in the Senate. This will slightly reduce the Republican majority. The Democrats would now only need two more senators to have the same number as the Republicans.

In 2020, the Republicans will be defending 22 Senate seats and the Democrats 12 seats. The most vulnerable Republican seats, according to FiveThirtyEight, are Maine, Colorado and Arizona.