The "Leitch Across America Tour" kicks off this week in the San Francisco Bay Area. (I'm aware that title sounds like a series of geographic inseminatory accidents. Just go with it.) Every couple of months, I'll be visiting a new city for a week, exploring the local sports culture, talking to fans and luminaries, attending games, and trying to figure out what makes the fanbases tick. The plan is to hit cities huge and small, from major metropolises to smaller college towns. The only way I know the world is through its sports; Leitch Across America is an opportunity to understand it better and put it into context -- a sort of Lonely Planet of sports.

We're still working out the kinks this week; we'll have this honed to a science after we do a couple of these. But for now, to quote the final "Calvin & Hobbes," It's a magical world out there. Let's go exploring.

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SAN FRANCISCO -- Every seat at AT&T Park in San Francisco is a gift. I think it might be the perfect baseball stadium. It's in an ideal location, with fabulous sightlines from every direction, impressively diverse beer selection and bathroom lines that never take longer than a couple of minutes or so. It is the sort of stadium that makes you want to watch every inning from a different spot, and every seat you're in, you think everyone else in the park is a sucker for not having a seat as terrific as yours.

Conversely, every seat at O.co Coliseum in Oakland is the same. You're miles away from the field, you're swallowed by the massiveness of a building clearly not meant to host baseball and no matter where you're at, it's likely the person behind you has their knees in your back. (If there is even a person behind you.) It's a pain in the arse to get out there, the infamous Mount Davis blocks what would be a lovely mountain view and, five minutes before first pitch, it's virtually impossible to move through the concourse. It's outdated and is holding back the franchises it houses.

In other words, the home parks for the Giants and A's couldn't be more different. And I still love them both.

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To be an A's fan, you really have to work at it. The BART trip out to the Coliseum is actually quite easy, but from there it's still a haul to the stadium and there's a palpable sense inside the Coliseum that you are away, from the rest of the world, from civilization, from outside life.

This has led to a fanbase that is devoted in a way that is rabid without necessarily being aggressive; quirky, bearded, loopy and irresistible. They're best typified by the raucous clan in the right-field bleachers, which our own Gwen Knapp last week called "the nerve center of this stadium." There are also a lot of older A's fans, the sort of lovable ones who bring scorecards and sharpened pencils to the game, the ones who listen to a pocket radio and wear the A's schedule on a lanyard around their neck. I saw several fans like this at The Field Irish pub behind home plate before Monday's A's-Giants game, including a surprisingly high number of "MCGWIRE 25" jerseys. The A's bring the old timers.

Because the A's need to fight and scrap for every fan they can get in the cavern that is their "ballpark," they have a lot of fun extras, from playing "The A-Team Theme" during introductions to promotions so cheap they sound actively unprofitable. (One Friday night deal offered four seats and four "dinners," whatever that constitutes, for $60. In New York I'm charged $15 bucks simply for leaving my apartment.) This manifests itself mostly, though, in an anything-goes attitude at the park. It is not a place where you notice a lot of security, let's put it that way. It can lead to bad times, but fun ones too.

I was curious what an A's-Giants game at the Coliseum would be like; I'm fascinated by intra-area matchups at the home field of the traditionally less-popular team. But this was no 50-50 split: It was mostly A's fans, and it wasn't particularly close. (The Giants fans who made the trip mostly stayed quiet, perhaps because they lost and/or were scared.) The only real difference you'd find between this and any other A's game was that, well, the stands were full.

Contrast that with the Giants-A's game Wednesday night at AT&T Park. There was a palpable edge to the proceedings, a sense that this lovely, almost stately, reflective park on the water was being invaded by ruffians from across the Bay. A's fans were loud, proud and throwing elbows, like a teen punk nephew wiping his nose on the linens at Thanksgiving when everyone else makes sure to take their shoes off at the door. At one point, an A's fan in the front row of his left field upper deck section kept standing up in the middle of play, screaming and spitting sunflower seeds everywhere. Despite repeated pleas of "Down in front," he stayed standing and yelling, mocking ushers and making a nuisance of himself. ("They tell us we can't tell people to sit down, as a rule," an usher explained, sighing.) There weren't any fights about it, though. The Giants crowd isn't as feisty, and mostly everyone just sat there until the fan punched himself out and finally sat down. And even he wasn't all that much of an a--hole about it. A few minutes later, the rowdy A's guy was jovially chatting with the Giants fans in his section. I love A's fans.

They certainly did represent: When Yoenis Cespedes tripled home a run in the first inning, there was a huge roar from the many A's fans in attendance, one Giants fans weren't quite able to replicate or counteract. (It didn't help that Tim Lincecum has lost all his magical powers and was out by the fifth inning. Again.) A Giants fan behind me snarled, "So they don't show up to their own games, but they show up to ours."

It's easy to understand why Giants fans might not be as rowdy as A's fans right now. Their stadium is almost the platonic ideal of a baseball stadium, and that sort of comfort can lead to stasis, the inertia of having every whim catered to. It can lead to a loss of edge. And you know what else leads to a loss of edge? Winning two World Series in three years. You can't really blame Giants fans for wanting to stretch their legs, relax and eat some garlic fries while A's fans hop and howl.

It made for kind of an ideal evening: Deeply invested, spirited A's fans in the pastoral setting of what might be baseball's best park. It's trendier to be Giants fan. It's more arresting to be an A's fan. They're both pretty great.

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Email me at leitch@sportsonearth.com, follow me @williamfleitch or just shout out your window real loud, I'll hear you. Point is, let's talk.