Yet there were moments when the rallies slowed — or were forced to pause — just long enough to resemble a traditional, stationary demonstration. One came on the afternoon of July 29, a Sunday, as 200 protesters walked south on Harbor from the Anaheim police headquarters toward Disneyland.
When they reached the intersection of Harbor and Ball Road, at the base of a modest rise that takes the boulevard over Interstate 5, they discovered a line of riot police and officers on horseback.
Over the next several minutes, as each side stared down the other, this wide Orange County crossroads, dominated on a typical day by cars and the trappings of car culture, revealed itself as a surprisingly useful public square.
The standoff was also very much in line with the rich if under-appreciated history of Harbor Boulevard, where street battles have played out for nearly a century.
Ku Klux Klansmen and the wives and daughters of striking citrus workers have played key roles in Harbor's most dramatic public spectacles. So have Abbie Hoffman's Yippies, who swarmed Disneyland in 1970 and planted a Viet Cong flag on Tom Sawyer Island.
These flash points have come irregularly, spasms of violence or protest theater on an otherwise buttoned-up boulevard. But the relationship between Harbor's physical character and its political history is closer than you might guess.
Harbor's architecture, largely anonymous and inward-looking, is marked by a studied blandness. Perhaps to make up for its shortage of impressive civic landmarks, the boulevard features a number of private spaces, including Disneyland, that look public but are in fact tightly controlled.
That recipe has produced on Harbor a feeling of unnatural civility — the architectural equivalent of a forced smile. And it has helped keep political tensions bottled up and out of view until they messily spill over, as they did during this summer's protests.
In that sense Harbor's history of turbulence has lessons to offer that have as much to do with urban design as politics. Like the CicLAvia bike festival and the recent tour of the Endeavour space shuttle, protest can open up new ways of looking at our streets.
It's on the extreme days, the unruly or topsy-turvy ones, that our boulevards show us most clearly what they might become. And Harbor continues to be very good at producing extreme days.
Though it covers 23 miles in all, Harbor Boulevard never quite makes it to the water. After running from the foothills above La Habra south through Fullerton, Anaheim, Garden Grove and Santa Ana, it peters out in the middle of Costa Mesa, two miles from the beach.
Harbor's name is therefore more aspirational than literal, and in that sense true to the spirit of Southern California expansion. So is the streetscape of the boulevard. With the exception of the area around Disneyland, where the sidewalks are generous and the tree canopy thick, Harbor is dominated by drive-throughs, auto-body shops, tire outlets and big-box stores.
And by intersections that are unusually wide: Crossing Harbor at Ball Road on foot means trudging across 10 shadeless lanes of traffic.
Even as the boulevards of Los Angeles have begun a remarkable transformation, opening themselves up to pedestrians and cyclists and chipping away at the dominance of the car, much of Harbor looks just as it did decades ago.
There is no equivalent on Harbor of the expanding light-rail network that is remaking Los Angeles. Although the Anaheim City Council has tentatively endorsed a streetcar system linking Disneyland with a planned transit center near Anaheim Stadium, for now — and for many years to come — the only rail service you'll see along this part of Harbor is the theme park's own monorail, which sweeps briefly into view on an elevated track.
In recent decades, the theme park has taken steps to seal itself off from the city around it. Caltrans added a dedicated offramp from Interstate 5, ending Harbor's traditional role as Disneyland's front door.
Anaheim, for its part, has slowly remade the stretch of Harbor that runs alongside Disneyland, homogenizing it in the process. In the 1990s, the city passed an ordinance requiring businesses near the park to replace their signs — some of them masterful examples of the space-age Googie style — with smaller ones meeting a uniform and remarkably bland design standard.