In the headlong plunge toward the midterms, what aren’t folks paying attention to? The universe of potential answers is infinite, from “gun control” to “the endoplasmic reticulum,” but data from Google can help narrow it down.

A map of Google searches for political issues in every county in the United States feels like a periscope. It pokes above the political rhetoric and media coverage and peers straight into the nation’s subconscious.

Crises wash over the country. Attention rises and ebbs. Issues that seemed decisive early in the year get zero traction in November. In February, the month 17 people were murdered at Marjory Stoneman Douglas High in Parkland, Fla., most of the nation searched for terms related to gun control. By October, the issue had fallen off the map.

Some things, of course, remain constant. When Google provided us with search data for more than a hundred politics-related issues, there was one obvious pattern. In almost every county in almost every month for the past year, health care topped the charts. Medicare and Medicaid were perennially popular, as was mental health.

Immigration, too, remained popular. These maps are monthly and end in October, but there’s evidence that in the closing days before the election, political rhetoric is breaking through. It now rivals health care at the forefront of the nation’s consciousness.

To understand which topics had fallen off our radar, we chose nine issues that had strong political ties and heavy search interest. We tried to pick issues of relevance across the political spectrum. It required a few judgment calls. Issues can overlap, and each of our chosen topics consisted of dozens or even hundreds of search terms that a Google algorithm has determined to be related. The algorithm combines searches in all languages.

When we removed health care from the mix, a few geographic patterns emerged. Immigration was easily the most popular non-health issue, especially in urban areas.

To better understand the geographic distribution, we sized circles by population instead of coloring in counties. To understand why, let’s consider searches for the Confederacy.

At first glance, the results appeared random. Searches for Confederate issues had little relation to the borders of the Confederate States of America. It’s a weird map.

Then, we represented counties by circles sized by population. We would have preferred search volume, but Google couldn’t provide that data. We found that the divide wasn’t between the North and the South, but between populous urban areas and less-populous rural ones. The tiny rural dots become harder to see, but the trend becomes apparent.

Searches for the Confederacy topped the list not just in the Deep South, but also in rural parts of states such as Colorado, Michigan and New Hampshire. In urban areas such as Detroit and Denver, however, those searches didn’t crack the top four.

The map illustrates a trend chronicled by the Post’s Frances Stead Sellers, who wrote in October that the Confederate battle flag had become a nationwide symbol of white grievance.

Here, we show April 2018 — when searches peaked during the controversy over Confederate monuments. October’s search pattern is similar, but interest has waned.

Other issues with higher search traction in rural communities since September include: agricultural subsidies, the Dakota Access pipeline, fracking, voting age, electoral fraud and flag desecration. Issues with high search traction in the most-populated fifth of counties included: the Patriot Act, free trade, political corruption, the Paris climate agreement, safe spaces and vaccine controversies.

Like gun control, tariffs captivated the nation early in the year -- especially in areas that depended on agriculture or international trade. But by October, only a handful of rural counties were still paying attention to the issue.

Interest in the minimum wage peaked in January when minimum-wage hikes took effect in scores of cities and states. It remains high.

When the pattern is different, it’s often for issues that tend to tumble around in the nation’s consciousness whether or not there’s a specific news story to thrust them into the nation’s headlines. One example is abortion, which was a high-ranked issue in the South and Midwest earlier in the year, but has now spread throughout the country.

We’re taking the long-term view here. You can find real-time maps, including many that compare politicians head to head, at Google’s midterms site. Click on specific states for details. Here’s Texas.

Google search data comes with many limitations. We can overcome some of them and compare numbers nationwide by isolating issues that ranked highest in each county. There’s one significant distortion from population density: Obscure topics don’t get enough search traffic in less-populated counties, so it’s more likely data won’t be available for rural areas. But where ranks are available, a Google representative said, they’ll be consistent.

This story and its headline have been updated.