Our first clue came on the last day of July, as my husband, Ken, and I prepared to leave Washington State for our Iowa home. Reserving motel rooms along Interstate 90 wasn't easy. Clearly, something was up.
But not until we'd bisected Idaho's panhandle did we notice them - motorcycles - their numbers increasing as we headed east.
As we crossed Montana, the scenery sometimes took a back seat to the spectacle of motorbikes buzzing around us like gnats.
At our next rest stop, a grizzled, leather-clad biker stomped down his kickstand and explained: He and an estimated 60,000 compatriots were headed for the week-long Black Hills Motorcycle Rally in Sturgis, S.D. It began that weekend.
Driving on, we imagined our stodgy white Dodge minivan as a plump, lumbering larva in the midst of these gleaming, beetle-like Harley Davidsons, our engine noise a muffled yang to the yin of their distinctive din.
Meanwhile, my Hell's Angels stereotypes were blowing out the window - and rightly so. One national news magazine had even declared: "forget the leather-clad outlaws. Today's bikers tend to be middle-aged, white-collar types out for recreation."
But initially, those white collars were well hidden. The average biker's garb put us more in mind of Darth Vader on wheels, though we learned that these uniforms were primarily practical: snug black-leather jackets and leggings help protect riders in case of a spill. But by trip's end, even the long-haired, sleeveless T-shirted, tattooed types reminded me not of some tough archetype, but of my computer-savvy stepson who also goes in for epidermal art and of my own motor-biking younger brother.
The bikers shared the highway courteously, behaving during layovers with ambassador-like affability. As their momentum swept us into Wyoming the next day, we waited in line with these stiff-legged folks at gas stations and waysides. Many smiled and nodded, striking up conversations as travelers will do. Seeing them in droves made us wonder what drove them.
Our curiosity was reciprocated by the grizzled gentleman at the Montana rest area, who had seen our cats peering out our windshield. After describing the rally, he asked how the kitties tolerated road trips. They're used to it, we shrugged. He looked skeptical.
His unspoken question, "But why do you travel like this?" mimicked ours to him.
While our respective answers might have sounded idiosyncratic (cat lovers can be fanatical, and owning a Harley is steeped in mystique), it struck me that in essence, our reasons might be simple, even similar, in some respects.
The next day, near Sturgis, a massive, eastbound motorcade of bikes engulfed us, then ceased abruptly as we passed the last exit. But just as suddenly, oncoming swarms appeared across the median. With bikes far outnumbering cars, the westbound freeway resembled a parade - with a parade's measured pace.
Tent cities filled several small fields nearby.
Agog, we kept driving. Only an hour later did the oncoming convoy begin to break up.
At a gas station just east of Sturgis, another friendly biker wiped the rain from her helmet as she lamented having to fly home two days later. It was easy to picture her business-suited, in an office. She seemed middle-class, middle-aged, Midwestern. Like us.
"I've always been afraid of bikes," Ken confided to her.
"Most people are," she said, "Unless they grow up with them."
"I've always been afraid of bikers," I thought, then realized that, categorically, I no longer was.
Traveling with this crowd was not quite a conversion experience, however. I was born to be mild. More worrier than warrior, I'll continue taking to the open road in closed vehicles only - at least as long as I'm traveling with cats.
By the time we crossed into Minnesota the next morning, we felt as if we'd seen all 60,000 motorcyclists. We were glad that we had. When we finally turned south onto I-35, the interstate seemed inanimate, ordinary once more.