NASHVILLE — A few years ago I started noticing wildflowers blooming beside the highway: ironweed and goldenrod and snakeroot and black-eyed Susan. The first time it happened the sun was in my eyes as I drove west toward Memphis, and a late summer drought was filling the air with dust motes. For a moment I thought I was imagining flowers where flowers had never been before. A daydream on a lonesome stretch of highway as twilight came on.

There was nothing unusual about the flowers themselves — they’re the plants that commonly bloom along Nashville’s greenways during late summer — but these flowers weren’t in a park or a nature preserve. They were growing right on the interstate median and on the side of the road. I figured the state’s Department of Transportation simply hadn’t gotten around to mowing yet.

Then I started to see the flowers in springtime, too, and all summer. The decision not to mow, it turns out, was deliberate. The Tennessee Department of Transportation — like many other state transportation departments across the country — now practices swath mowing, a strategy that allows wildflowers to bloom unmolested in rural areas till after the first frost. Instead of clearing the entire space between the road and the right-of-way fence, mowers clear only a 16-foot-wide area next to the road.

The mowed swath preserves clear sightlines for drivers while allowing wildflowers to grow in the deep margins between the mowed area and the fence. After the wildflowers have gone to seed, and the seeds have had time to ripen and drop, mowers clear the entire area again to keep trees from becoming established too close to the road. In Tennessee, this plan began as an experimental program in 2013 and now encompasses all rural highways managed by the state. That’s 13,807 miles of blooming flowers across Tennessee.