The country's ongoing drug epidemic, which claimed more than 59,000 lives last year, has left its trace on just about every aspect of American life: politics, religion, family, justice, birth and death.
While most of us are familiar, by now, with the annual drumbeat of official statistics from places like the Centers for Disease Control and Prevention, online search data offers a window into facets of the epidemic that traditional numbers aren't great at catching.
One of those is drug withdrawal, the often extremely unpleasant symptoms experienced by people dependent on a substance - whether it's heroin, marijuana, alcohol or something else - when they try to stop using it.
Data from Google Trends shows that search interest in all topics related to drug withdrawal has roughly doubled over the past decade. Some unknown percentage of these searches are probably from curious people simply looking to learn more about what happens when a person stops using drugs. But several pieces of evidence suggest that these figures reflect a sizeable number of searches from drug users themselves.
For starters, the searches are concentrated in the regions where we know, from mortality data, that the drug epidemic is raging most fiercely.
In 2015, for instance, the states where people were most likely to search for drug withdrawal on Google included West Virginia, Kentucky, New Hampshire and Ohio - the four states with the greatest incidence of overdose death that year, according to the CDC.
Other drug-related search topics, such as substance abuse, addiction or even opioids, don't correlate nearly as well with the mortality data. That suggests that drug withdrawal searches are more closely linked to people actually using drugs.
Another piece of evidence suggesting the withdrawal searches track actual use patterns is their seasonal fluctuation.
Year after year, these searches follow a similar pattern. Interest in withdrawal is highest at the start of the year, perhaps due to drug-dependent individuals making resolutions to quit using.
But interest drops off sharply, inching up again slowly until it hits a secondary mid-summer peak. Vacations, nice weather and a relative reprieve from the mental stressors that make life difficult may induce some users to try quitting when the days are long.
Interest in withdrawal declines through the end of the year, particularly crashing during the weeks of Christmas and Thanksgiving. The holidays are a well-known trigger for substance use in many people, and the lack of interest in withdrawal at the end of the year suggests that many people aren't mentally in a place to quit using while dealing with the memories, emotions and stresses of the holiday season.
If we accept that the Google withdrawal data track actual drug use, what are the implications? First, that the beginning of the year represents a crucial opportunity for friends and family members to offer support to loved ones trying to kick the habit. Treatment providers, support groups and public health agencies may want to consider upping their outreach efforts at this time of year, the better to help people struggling with quitting who may not have otherwise have support at home.
Second, Google provides another potentially valuable tool for public health experts: real-time search data at the metropolitan area level. In the past week, for instance, that data showed a spike in withdrawal searches centered around the town of Alpena, Mich. Searches for "overdose" are spiking in Ohio and Maine.
What's happening this week in Alpena; or Youngstown, Ohio; or Presque Isle, Maine? Public health researchers may be able to use these numbers to track drug outbreaks as they happen. Researchers in Europe, for instance, are experimenting with using Google data to predict methamphetamine-related crime.
Finally, along with the mortality figures from last year, the even more recent withdrawal interest numbers show absolutely no indication of abating. Seasonal patterns aside, the interest in drug withdrawal in July 2017 is currently the highest it's ever been in Google's 13-plus years of data. That suggests that we still may be far away from turning a corner on the current epidemic.