By Steve Rubenstein

San Francisco Chronicle

SAN FRANCISCO — Eclipse camping trips, eclipse horseback rides, eclipse steamboat excursions.

Eclipse whiskey tastings. Eclipse cowboy adventures.

Seventy-dollar motel rooms marked up, on eclipse eve, to $1,000. Take it or leave it.

Cashing in on a good thing is a constant of nature, every bit as much as the heavens above. It’s the American way. On the morning of Aug. 21, a good part of the U.S. will be trying its hardest to turn a buck on that rare celestial phenomenon known as a total eclipse of the sun.

It’s big. It’s the sun. It’s going away, sort of. That’s as big as it gets. Even if it’s nothing more than a shadow, a fleeting darkness, a heavenly hiccup or — cynics might say — essentially nothing.

For those who look up Aug. 21, as well as for those who don’t, the moon will pass directly between the sun and the Earth.

But this one is rarer than most. The last time an eclipse spanned the entire U.S. was in 1889, when Grover Cleveland was president and Parisians were still trying to finish building the Eiffel Tower.

Most viewers will see a partial eclipse, with parts of the sun always visible. But viewers in a 70-mile-wide swath of land running from Oregon to South Carolina will see a total eclipse for a little more than two minutes.

Much of the eclipse trade seems devoted to persuading Americans who are not in the path of totality that they are missing out by settling for a partial eclipse.

San Francisco Bay Area watchers, for instance, will see a partial eclipse. The closest spot to the Bay Area for witnessing the eclipse in full is smack in the middle of Oregon, 450 miles away. It means an all-day drive on Interstate 5, sharing the highway with who knows how many eclipse chasers.

“It will be unprecedented,’’ said John Moreno, spokesman for the Auto Club of Northern California, who is advising eclipse-bound motorists there to stock their cars with water, food and emergency supplies, and to be prepared for traffic jams of astronomical proportions.

Over the Fourth of July weekend, Moreno said, 44 million Americans took to the road. The number of eclipse motorists will likely be similar. But on typical holidays, motorists head in all directions. For the eclipse, most will be heading on Interstate 5 to a narrow swath of Oregon.

“Usually, the destinations are spread out like a spider web,’’ Moreno said. “For the eclipse, they’ll all be funneling north. We’re in uncharted water for this.’’

In Oregon, accommodations are either unavailable or overpriced. Two motel rooms at the Rodeway Inn in Lincoln City remained available late in the week, priced at $999 each. On days when the sun is not hiding in the moon’s shadow, the same rooms go for $71.

“I haven’t seen anything like this,’’ said the hotel desk clerk, who declined to give his name because it’s somewhat embarrassing to ask $999 for a $71 room. “It’s not my place to say if we’re charging too much. All I can tell you is that I couldn’t afford to stay here on Aug. 20.’’

In Salem, Albany and Corvallis, the main Oregon towns along the I-5 corridor in the path of totality, there are no rooms left at any price, according to online booking sites.

There do remain a few lodging options in the state, mostly for people willing to camp. In northeastern Oregon, the athletic field at Baker City High School is being turned into a giant tent city.

On the other side of the state, the rodeo grounds in Philomath, west of Corvallis, are available for tents, too. A site there, also including portable-toilet access, is only $150.

History will be made when the minor league Salem Volcanoes halt their 9:35 a.m. baseball game against the Hillsboro Oaks in the middle innings to allow fans to watch the eclipse. An $8 bleacher seat at the Salem stadium is being jacked up higher than an infield fly — to $60. The team, on its website, says it’s the “first professional baseball team to have a planned delay to a game (for an) eclipse.’’

Back in the Bay Area, sky watchers will see only a partial eclipse — 76 percent of the sun will be covered. That’s not good enough for Ian Berke, who plans to fly to Salt Lake, pick up a car and drive to a rented house in Idaho, in the path of totality, that a friend is letting him share — for $400 a night.

“Sure, it’s only two minutes but it’s an overwhelming two minutes,’’ said Berke, a San Francisco real estate agent who saw an eclipse years ago in Mexico. “I’m tongue-tied, trying to describe it. It’s overpowering. It’s awesome. Words fail me.’’

Heading to Central Oregon is retired San Francisco attorney Elaine Affronti, who said a total eclipse of the sun is worth crossing state lines for.

“The stars are going to come out in the middle of the morning,’’ she said. “That’s amazing. It’s fantastic. I’m 71, and I doubt I’ll have the chance to see another one.’’

Maybe, maybe not. In the 20th century, there were 228 solar eclipses. In the 21st century, there will be 224 solar eclipses. Most are partial eclipses and most do not sweep across the entire U.S., as the Aug. 21 eclipse will do.

As a lawyer, Affronti knows there is probably no one to sue if the eclipse gets upstaged by fog, clouds or overcast. A legal contract is only valid if you can hold the other party to it, she said, and with an eclipse it’s not clear who the other party is.

“No legal remedies,’’ she said. “Nothing you can do.’’

The eclipse is guaranteed. It will happen. It’s a sure thing. Seeing it isn’t.

“Don’t say the word ‘clouds,’’’ said eclipse tour organizer Victoria Sahami. “I try not to say that word, ever. I try not to think it.’’

Sahami, a Denver tour agent, has chartered no fewer than 17 buses and taken over an entire Wyoming dude ranch for the Aug. 21 eclipse. She plans ahead. Three years ago, she reserved her first charter bus for the event. When that filled up, she reserved 16 more. Those filled up, too.

That means she will be hauling around 1,000 eclipse fanatics, at $200 a head, from downtown Denver to a hilltop in Wyoming. Each customer gets a turkey sandwich and a “genuine pair of eclipse glasses’’ that Sahami bought in bulk. (When you buy eclipse glasses in bulk, she said, they cost 50 cents each.)

If a cloud is hovering over the prime viewing spot in Wyoming, she’ll load everyone back onto the 17 buses and zip to a nearby, uncloudy place — or, at least, she’ll give it a try. It’s something like a quarterback calling audibles at the line of scrimmage. Sometimes it works, sometimes not.

“I can’t make any promises,’’ she said. “How could I?’’

Sahami knows what it’s like to host disappointed eclipse chasers. In 2000, she brought a group of them to China for a total eclipse. But a typhoon had passed through days before, and her customers were socked in by thick clouds along with much of the rest of the country. Sorry, no refunds.

“It wasn’t our fault,’’ Sahami said. “Everyone knew it wasn’t our fault. But none of them booked a tour with us again.’’

If the worst happens, weather-wise, perhaps a good place to watch the eclipse will be something called the Eclipse Bourbon Masheree, a party and bourbon tasting in the Kentucky town of Hopkinsville, which has taken to calling itself Eclipseville USA.

From coast to coast across the path of totality, small towns in need of an economic lift are working all the angles. A Wyoming hotel is hosting eclipse yoga. A Missouri town is throwing an eclipse barbecue.

The Nashville Symphony Orchestra in Tennessee has booked itself an outdoor eclipse gig.

With regard to eclipses, clouds do not have a silver lining. When it comes to things passing between the Earth and sun on eclipse day, the moon is welcome and a cloud is not.

In lieu of a money-back guarantee, eclipse fans can play the odds. The Bear Basin Adventures company is hosting a three-night camping trip by horseback to an 11,000-foot viewing spot in Wyoming. The price is $2,800, and you have to give the horse back.

“The odds are in our favor,’’ said the company’s website, which also says the trip costs more than twice as much as similar trips when the sun isn’t disappearing.

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