Even though Democrats narrowly won a majority in the Senate this year, the institution as a whole still gives Republicans a massive undue advantage—and has done so for decades. To illustrate this, Daily Kos Elections has compiled a spreadsheet that calculates the popular vote for the Senate going back nearly three decades and also shows the proportion of the country’s population that senators from each party represent.

The implications of this data are astonishing: As shown on the chart below, Senate Republicans have neither won more votes nor represented more Americans than Democrats since the late 1990s. Despite that fact, the GOP has controlled the Senate just over half the time since then, a development that has not gone unobserved.

Senators are of course elected to staggered six-year terms, with a third of the chamber up every two years. To determine the popular vote for any given Senate, therefore, we’ve combined each party’s vote totals for every Senate election over a three-cycle period. However, since different election years have differing levels of voter turnout that complicate the task of aggregating votes across multiple years into an accurate gauge of public sentiment, we have also calculated the proportion of the 50-state population represented by each party in a given election year, although both metrics nonetheless yield similar outcomes.

The figures for 1998, for instance, include all Senate contests from that year as well as 1996 and 1994, plus the share of the population represented by the senators elected in those years. Taken together, as you can see in the chart below, they show the GOP with a narrow 50-48 advantage—the last time Republican senators won more votes than Democrats. And you have to go back two years earlier to find the most recent occasion when Senate Republicans represented more of the nation’s inhabitants than Democrats.

Senate popular voteRepublican minority rule in the Senate has already had far-reaching consequences. Five Supreme Court justices (and many more lower court judges) were confirmed by senates where the GOP majority was elected with less popular support than Democrats. Those right-wing hardliners are now poised to use their control over the court to attack voting rights and preserve Republican gerrymanders while striking down progressive policies. This same minority rule has also paved the way for massive tax cuts for the rich under George W. Bush and Donald Trump that have facilitated an explosion in economic inequality.

The Senate’s mal-apportionment and bias toward rural white voters who favor the GOP in disproportionate numbers has become the most critical institutional threat to democracy, even more so than the Electoral College. Given the propensity of the party controlling the White House to lose seats in midterm elections, there is a significant risk that Republicans will regain the Senate in 2022 even though Democrats may once again win more votes and represent more people than the GOP, and this threat of minority rule will continue for years to come.

Put another way, Democrats need to roll up decisive wins in multiple election years just to have a shot at a bare majority. But with the nation’s population increasingly concentrated in just a handful of large states that control a tiny fraction of the Senate, the chances for majority rule could grow still worse in the coming years.

And this barrier doesn’t even address the Senate filibuster, an accident of history where the main use has been to block civil rights laws and now asymmetrically benefits the GOP. Republicans’ main priorities of enacting tax cuts for the rich and appointing conservative judges can already be managed with simple majority votes while Democratic priorities such as safeguarding voting rights, protecting the environment, and reforming democracy require super-majorities.

Trotting out the insidiously misinformed catchphrase “we’re a republic, not a democracy,” Republicans like to claim that the framers of the Constitution abhorred democracy and that institutional minority rule is a sacrosanct part of our constitutional order, but these arguments could not be more wrong. While the framers disapproved of direct democracy, they repeatedly made clear that they sought to create a system of representative democracy where the majority rules with limits, not where the minority rules—in other words, a democratic republic. 

The Senate’s structure did not come about as a reflection of some high-minded ideal but rather was a compromise between self-interested delegates from small states seeking to protect their power and delegates from larger states who favored equal representation based on population. Yet even when the Senate was originally established, the largest state only had 13 times as many people as the smallest state. That difference has ballooned over the ensuing centuries, with California now at 68 times the size of Wyoming.

Fortunately for the movement to make our electoral institutions fairer toward the parties and to voters of color, Democrats have one key tool available that could modestly help rebalance the Senate playing field: admitting new states by ending the disenfranchisement of four million mostly Black and Latino citizens in Washington, D.C. and Puerto Rico, respectively. Doing so would only require a simple majority vote—if Democrats agree to curtail the filibuster—rather than a new constitutional amendment.

Congressional Democrats have already introduced a bill to grant statehood to most of Washington, which House Democrats passed last year, following on the overwhelming support for statehood by Washington voters in a 2016 referendum. A statehood push is also underway for Puerto Rico, which passed a non-binding referendum in support of the idea just last year.

In the 19th century, the admission of new states was frequently a tool for reshaping Senate politics. When faced with tenuous majorities threatened by white supremacist voter suppression in the South, Republicans under President Benjamin Harrison solidified their hold on power not by protecting the rights of Black Southerners but by admitting six sparsely populated northwestern states in 1889 to 1890, including splitting the Dakota Territory into two states. This decision by Gilded Age Republicans to gerrymander the Senate long ago still happens to favor the party today.

But even if Democrats admit Washington, D.C. and Puerto Rico as new states, doing so would only modestly reduce the Senate’s considerable biases toward Republicans and against voters of color, not eliminate them, since the median seats in the chamber would still lean more conservative and whiter than the nation as a whole.

Over the long term, more far-reaching measures will be needed. The British, for instance, stripped from their upper chamber, the then-reactionary House of Lords, the power to block bills approved by the House of Commons over a century ago. Relying on a single chamber of government is possible: Nebraska eliminated its state House and adopted a unicameral legislature in 1934, while Washington, D.C. is governed by a single 15-member council.

Of course, proposals like these would require either a constitutional amendment—which the GOP would oppose—or an outright break with the constitutional order much like the framers did when ditching the Articles of Confederation in favor of the Constitution. Admitting new states is therefore the most realistic option for preventing the Senate from becoming even more entrenched as a bastion of white Republican minority rule.