Walking through the Town Park campsites on Tuesday night was like walking through a time capsule.

These people have been here, doing this, for years.

Even before the 36th Annual Telluride Bluegrass Festival comes to town this weekend, there has been a flurry of oldtimers picking banjos and guitars, friends crowding into oversized tents and music morning, noon and night.

And while the festival itself has evolved in its nearly four decades of life, and now brings to town some of the best musicians in the world, festival officials, for the most part, know not to fix what isn't broke.

On Tuesday, visitors crowded into a “room” in a campsite near the river, milling under tarps strung between trees sectioning off components of a tent-mansion. This was the room, to be precise, with the booze and the music, and what started as a low-key nighttime performance from an Arizona-based band ended a few hours later in an eight-piece jam bringing out the classics – let’s just say it was not the first nor the last time that night that Town Park campers would hear Townes Van Zandt's “White Freight Liner.”

Longtime Festival Director Craig Ferguson says that year’s festival rests on the same pillar as always: The bluegrass community of “festivarians” – a word, incidentally, he says he invented – that’s applied to the thousands of festival attendees.

And for the Telluride Bluegrass festivarians – who are, really, “the Telluride Bluegrass community,” Ferguson says, which “is just so deep” that, whatever their role in this weekend’s event, for most of them, attending this festival year after year is a tradition.

Ferguson says this far-flung bluegrass festivarian community lends itself to a less-than-traditional festival.

Take Conor Oberst and David Byrne, for example – not exactly bluegrass stalwarts, but that doesn't mean they're not closing the first night of the festival.

Ferguson’s pleased that bluegrass festivarians of all stripes look forward to the four-day Telluride Bluegrass program, featuring everything from longtime fixtures like the “house band” comprised of Sam Bush, Jerry Douglas and Béla Fleck to genre-stretching superstars to new acts to even, he says happily, “oddballs,”

But though he admits it's not a traditional bluegrass festival, he firmly believes that the best bluegrass musicians play here every year.

“When those guys are up there, you don't think of them as music impresarios,” Ferguson says of the House Band’s Bush, Douglas and Fleck and friends. “You think, 'These guys are playing at a backyard hootenanny and having a great time.'”

Sam Bush, known here as “the King of Telluride,” for example, has been playing the Telluride Bluegrass Festival for 34 of its 36 years. For Fleck, make that 27, and for Douglas, 25. And every year, they’re just a few of the world-renowned artists who come together every year, over the summer solstice, to make the Telluride Bluegrass Festival a mecca for music-loving festivarians.

Of the festivarian performers, Ferguson says, they play Telluride because they want to (although the leather sofas and southwestern décor of the luxurious backstage “Cowboy Tent” where performers go to relax just might be a draw, as well).

“All those guys live in Nashville, but the only time they actually see each other is backstage at Bluegrass,” Ferguson says of the recurring artists, who are just one example of how the Telluride Bluegrass Festival works as a well-oiled machine. Ferguson says are few kinks in the planning, thanks to a crew whose members have years of experience (and those with more than 15 years of experience have new jackets to prove it) and who are quietly working behind the scenes long before the gates open Thursday. These days, Ferguson says, all he has to worry about is making sure his two kids don't get into trouble – the festival, to all outward appearances, runs itself.

Of course, the tough part for Ferguson is Telluride region politics, and every year, he negotiates with local governments and their businesses whose officials, sometimes, underestimate how much money this Telluride perennial puts in their coffers, and overestimate how much it can pay them for certain amenities, like transportation and parking.

“It takes a lot of work and risk to pull this off,” Ferguson says. “It's not so much the money, but the time it takes to chitchat about how this festival will bring millions to the community.”

He points out that during Telluride Bluegrass Festival, the region boasts its highest occupancy of the year – “we're more dependable than Christmas,” he declares – and that the money going into restaurants, bars and retail helps Telluride businessowners get current on their loans.

This year’s tight economy affected this year’s festival, Ferguson acknowledges, but says he's not too worried. Though ticket sales were a little off, the festival is expected to sell out Saturday, and the Town Park campground is already full. Festival officials tried to cut some corners, slashing the budget about 15 percent, but Ferguson says there was only so much to cut – the world-class musicians, after all, have to be paid.

“People say, 'Telluride is so beautiful, he'd probably come here for free,'” Ferguson says of the talent he draws to the Telluride Valley. “Well, maybe he would, but we're talking to his agent who's talking to his manager who's talking to his wife.”

Another area where he has not scrimped is the festival’s sustainability. Its green initiatives began eight years ago at the KOTO Beer Booth, where patrons were charged for the cups they used. Now the festival composts its trash and awards prizes to campsites that are the most “environmentally friendly.”

Today’s festival is carbon-neutral, estimating beforehand the carbon footprint of festivarians' travel, and offsetting that by subsidizing wind-power plants. Planet Bluegrass's focus on renewable energy led Colorado Governor Bill Ritter to declare June 23 Colorado Bluegrass Day in 2007. This year, the festival has invested in dishes and a dishwasher, so the crew and artists can avoid using disposable utensils and plates.

All this leads to what Ferguson describes as a “high-class” event.

It's one that has gotten smaller over the years. In 1991,16,000 people attended Telluride Bluegrass; now the festival has been overtaken by large-scale productions like Tennessee's Bonnaroo.

But that doesn't mean it has lost its luster. Ferguson says that little details – like how hard it is to get to Telluride, and the fact that it only uses one stage – help keep this weekend unique.

“We've maintained our reputation of ‘music first, genre last,’” he says. “It's about the music and not about the party. Which is not to say that we don't have a good party.”

And this party has been raging all week, as celebrants have streamed into town. Whether they're staying at Capella or at a Town Park campsite, everyone's whistling bluegrass.