What does it mean for a country built around the car to run out of road? That’s what David Levinson at his “Transportationist” blog indicates may have happened while our national attention was consumed with the Great Recession, somewhere between 2008 and 2011. The many ways to measure roads obscures our ability to pin down just the point when we hit “peak road,” and highway lane expansions will likely increase the total acreage paved for some years to come. But, as Eric Jaffe notes over at Atlantic Cities, “new lane miles won’t add great economic value (since they don’t create new access routes) and will only temporarily relieve congestion (since they ultimately encourage new cars onto the road).” The end-to-end length of our roads, measured in “centerline miles,” seems to have run out at 2,734,000 miles.

It might seem a rather arbitrary milestone to take note of, the total length of our roads. After all, social science gives us a multitude of metrics seemingly more suited to measuring and quantifying our social states. The General Social Survey every two years releases volumes of data tracked rigorously across decades on political attitudes and lifestyle decisions. The Bureau of Labor Statistics monthly releases job reports that set the conventional wisdom as to the strength of the economy, with its accompanying political credits or demerits. The Census Bureau, decennially counts every person in the country, along with a host of distinguishing demographic data. Why, then, pay attention to the pavement?

Because our roads are the received and transformed legacy of the American Frontier. As Patrick Deneen recounted a couple months back, Frederick Jackson Turner’s landmark study “The Significance of the Frontier in American History” noted the official close of the frontier as recorded by the 1890 Census report, when there was no further line to be pushed out into by isolated settlement. From then on, the American adventure spirit that had always held the possibility of lighting out into new discovery had to turn around, and take stock of the suddenly limited land around it. Rail would be laid, and roads built, crawling the wilderness with pathways of civilization. America went from an outward-facing nation to an inward-facing one, exchanging unlimited bounty for density and connectedness. Yet the free spirit of the frontier was not altogether lost.

As Ari Schulman wrote in his excellent 2011 New Atlantis essay “GPS and the End of the Road,” “Even once the Americas had been crisscrossed with rails and paved roads, a new age of discovery was opened—the age of personal discovery celebrated in the mythology of Kerouac and the open road.” As the roads grew before us, a car provided an escape to, if not the wild, at least the novel and the new. New people, new towns, localities being newly opened up or communities newly connected allowed us to learn from this sprawling country of ours, and learn about ourselves through their pursuit.

It takes on a different tinge, though, when you know the road is shrinking back towards you. Mobility allowed us to escape the strictures of place, as Deneen described, attenuating our connections to home as we built new ones around the nation. Shrinking, though, can make for a very different kind of smallness than that championed by the localists mobility left behind. As the open road recedes, how will the restless American spirit take to density?