WHITNEY PORTAL — The headlights begin streaming by at 11 p.m., just as you're finally nodding off. All night long, they go past, at steady 10-minute intervals.
At 2:30 a.m., the campground is a bustle of activ- ity. Voices murmur in the darkness. Car doors shut. Flashlights illuminate distant trees. Time to chow something down for breakfast, and get moving.
By 3:30, you're on the trail. The sliver moon above doesn't provide much light, so headlamps are a necessity. At one of the first switchbacks, you glance up and see a procession of tiny lights. Like an army of ants headed up the hill.
Sound like an unusual day in the Sierra? On the Mount Whitney Trail, it's like this every day during the busy months of summer and early fall.
The attraction is obvious. Mount Whitney is the highest mountain in the lower 48 states (even though government agencies can't seem to decide exactly how high it is), and hikers from all over the world want to stand on its summit.
Because the demand is so great, a quota system has been implemented that limits trail usage to 100 day hikers, 60 overnight hikers and 25 exiting backpackers every day from May 1 to Nov. 1.
That's 185 people, but you'd swear there's more.
The kicker is that it's an 11-mile hike from Whitney Portal to the summit via the trail, with a monstrous 6,140-foot elevation gain and that's only halfway. So if you're planning to complete the hike in one day, as many do, better get a predawn start.
"It's truly a 24-hour trail," backcountry ranger Rob Pilewski said.
Which makes Mount Whitney kind of like the Denny's of Sierra hikes. It's always open.
The Mount Whitney Trail does not follow the most direct route used by climbers and mountaineers. Instead, it ascends the gentler main branch of Lone Pine Creek past meadows and lakes until reaching Trail Camp (elev. 12,000 feet), 6.3 miles from the trailhead.
Trail Camp is where most overnight hikers set up their tents, and the rocky, alpine basin is dotted with them. (Human feces used to be a common sight up here as well, but human waste-disposal bags are now mandatory.) Now stretched before you are the infamous 97 switchbacks.
For the next 2.2 miles, the trail zig-zags its way up the mountainside. By the time you top out at Trail Crest (elev. 13,600) and peer down into Sequoia National Park, you've gained another 1,600 feet.
Just making it this far is an accomplishment, one that normally would be reserved for experienced hikers. But, again, this is Mount Whitney.
Two brothers from India, wearing jeans, white Nike tennis shoes and carrying travel bags with airport tags from LAX still attached, are especially excited to be here. One breaks out his camera and asks whether they're on the summit.
Uh, no. I tell them it's still 2 miles away but worth every step. They seem disappointed.
The final stretch along the Sierra crest isn't steep, but by now fatigue and thin air are conspiring against you. At least the summit is visible. It just seems a long way off.
The trail gets rockier and more exposed as it makes its way up the final slopes. At last, you spot the roof of the Smithsonian Institute Shelter, built in 1909 for scientific study, and realize you've made it.
Just as quickly, you realize you're not alone. Several dozen hikers are spread out across the flat, broad summit. Most are taking and posing for photos, chatting on their cell phones and updating their Facebook statuses.
Nope, there's no escaping technology. Not even at 14,500 feet.
Actually, there's disagreement over Mount Whitney's precise elevation. For years, the official number was 14,494 feet based off a stamped benchmark placed on the summit by the U.S. Geological Survey. (There's also a nearby plaque that says 14,497.) Except these figures are based on old methodology. Using newer vertical datum that takes into account Earth's actual shape (the geoid), Mount Whitney is now estimated to be 14,505 feet high.
In April, Sequoia National Park issued an updated "fact sheet" that changed Mount Whitney's elevation to the new 14,505 number. Weeks later, a retraction was issued because the new figure had not received official approval.
So according to the park service, Mount Whitney's official height remains 14,494 feet.
"There's disagreement about many mountains," USGS spokeswoman Leslie Gordon said. "But because Mount Whitney is so prominent, people notice."
After snacking and soaking up the summit views, it's time to head back. On the way down, you encounter many of the hikers you passed on the way up, including the two brothers from India looking seriously taxed.
It's 5 p.m. by the time you return to Whitney Portal, fried from exertion and lack of sleep. The trailhead parking lot is a lot emptier now, but it'll be full again soon enough.
This is Mount Whitney, after all, where the traffic never ends.
Mount Whitney Trailhead
Whitney Portal is 13 miles west of Lone Pine. The road is usually open from May to early November.
Total mileage elevation gain: 22 miles/6,140 feet Permits: Required year-round for all visitors entering the Mount Whitney Zone. Daily quotas are in effect from May 1 to Nov. 1. Permits awarded though an annual lottery.
Lottery: Applications must be postmarked between Feb. 1 and March 15 and accompanied by a $15 per person fee. Results are available by April 1.
Contact: Eastern Sierra InterAgency Visitor Center, Junction Highway US 395 and SR 136, Lone Pine, CA 93545; (760) 876-6222.
On the Net: www.fs.usda.gov/inyo.