To mark the end of 2018, we asked writers to revisit some of the year’s most noteworthy (for good or evil) events, people and ideas. See the other entries here between now and the new year.

Was it a blue wave? A blue tsunami? Or a blue trickle? That’s been the debate of the chattering classes since November’s midterm elections. Even before Nov. 6, the question of whether Democrats would score a major victory or whether Republicans would maintain a red wall of defense around President Donald Trump dominated the year’s political coverage.

That’s not a surprising framework for understanding an election year. Yet the obsession for much of 2018 with handicapping the upcoming election, and the microanalysis of the results in the weeks since, reveals both a misunderstanding of what is really happening in American politics and a deeper problem with our political commentary.

If a forest is often missed for the trees, it may also be that sometimes you can’t see the ocean for the waves. To conclude that a blue wave has crashed on Congress overlooks the much more significant political development of 2018: This year was about a blue base being built across the nation, one that that will support a durable Democratic majority going forward.

Democrats retaking the House by picking up the most seats since 1974 and winning the popular vote by an astounding 8.6 percent certainly indicates this was a landslide election. But it’s also important to note where those victories piled up, and what they suggest about a political realignment underway.

Democrats won by capturing the suburbs and turning the Midwest back their way. This road map to victory closely resembles how the Republican Party rebuilt itself during Bill Clinton’s presidency in the 1990s, establishing a bulwark in the nation’s suburbs and its heartland.

That strategy helped the GOP conquer state legislatures, control legislation at the state and local levels, and build a base of support for national dominance, culminating in 1994’s Republican Revolution that gave Congress back to the GOP and laid the groundwork for George W. Bush’s successful run for the presidency in 2000.

With Trump in office, however, much of what had been dependable red territory began to look like fertile ground for the Democrats. That proved especially true in the suburbs. Over the last 30 years, the modern Republican Party had turned white suburbanites into a solid voting bloc by emphasizing fiscal conservatism and national security. But since 2016, those messages have been drowned out by the president’s unrelenting bigotry and caustic style, an especially toxic brew for suburban women voters.

While soccer moms may never put “Resist” bumper stickers on their SUVs, they have been quietly shifting their party registrations away from the GOP. That meant big gains for Democrats in some unlikely spots, like Oklahoma’s 5th District, where a Democrat won for the first time in 44 years. And it yielded all seven House seats for the Democrats in Orange County, California, once one of the GOP’s reddest strongholds.

Some have argued this suburban switch is just a momentary response to Trump, not evidence of a more lasting realignment. But that misses how thoroughly Trumpism has overtaken the Republican Party, and how deeply he has tarnished the GOP brand in suburban enclaves. At this point, it’s difficult for any GOP candidate to disown Trump’s misogyny, and women voters have also indicated they are rejecting the party’s positions on health care, immigration and gun control. By losing America’s suburbs in 2018, the GOP may have lost its national prospects for a generation to come.

Like the Republican Party of the 1990s, the Democrats also gained significant ground throughout the Midwest, turning four governor’s seats and flipping Republican-held congressional districts in Illinois, Iowa, Kansas and Michigan. Ohio actually looks more safely red now, but the purpling of the Midwest, especially its suburban districts, has given Democrats a much broader network of support in the region than they’ve enjoyed for quite some time.

Coupled with impressive showings in Georgia and Texas, those wins in the Midwest suggest the Democrats will be playing with a very different political map than they have for the last three decades. In 2018, Democrats were able to compete in far more districts than they normally have, and the party will build from important wins in places like Arizona, Nevada and New Mexico. Even in many places where Democrats lost, they were able to run close races that forced the GOP to spend more money than usual and raised Democrats’ expectations for victory there next time. In Texas, for example, every Republican incumbent won their 2018 race by a smaller margin than they had in 2016. Some of those Republicans probably will not survive 2020, especially as the state grows more diverse.

Building out that competitive landscape will be one of the Democrats’ chief priorities heading into 2020, just as Republican activists expanded their party’s battleground territories in the 1990s. Yet unlike the conservative extremists who led the GOP’s expansion in that decade, the blue base is being built by Democrats from across the party’s political spectrum, from suburban moderates to progressives and socialists.

Democrats also won by mobilizing a much younger and more diverse electorate, while Republicans dominated with the shrinking pool of older, white voters. That diversity likewise characterized the Democrats who ran for and won elected office. Driving it all was the remarkable enthusiasm that brought out nearly 61 million Democratic voters, a number that almost equaled Trump’s tally in 2016 and that dwarfed the 45 million Republican voters who accounted for the GOP’s last big congressional wave in 2010.

Political commentators, hoping to stir up controversy, may point to the party’s ideological and demographic factions as a sign that the Democrats lack a clear agenda and haven’t settled the Hillary-Bernie debate of 2016. But the party’s diversity is its source of strength, not a liability ― the proof of a broad coalition that can bring still more Americans into the party and produce additional victories across the country.

Certainly, Trump’s presidency generated an election that looked like a blue wave. But the deeper work of defending American democracy against the awful specter of Trumpism has laid the foundation of something far more substantial.

Neil J. Young is a historian and the author of We Gather Together: The Religious Right and the Problem of Interfaith Politics. He hosts the history podcast “Past Present.”