My first clue that something had changed forever was the police.

In bright yellow vests, they descended on the area, guiding rush hour traffic out of parking garages and into the streets, down Harrison and onto Fairview.

At lunch, the line for the taco truck was clear around the block.

“Why do we all keep building tech startups?” I asked a friend. “Think about the profit margin on that taco truck.”

In retrospect, it was pitifully naïve – this idea I had that there would forever be one food truck on the corner of Republican and Boren. The face of South Lake Union was changing, and I was focused on burrito access.

Before the basement offices of Founder’s Co-op became home to Zipline Games, they housed a number of startups, including Startup Weekend and Seattle 2.0 (which would later be acquired by GeekWire). I wrote a weekly column for Seattle 2.0, and on occasion I worked from those offices, windowless and clockless and exceptionally bent to singular focus. (“It’s like Vegas,” commented then-CEO Jennifer Cabala.)

As soon as it opened, Founder’s Co-op’s South Lake Union location felt revelatory, a much-needed breath of fresh air from the Belltown, Capitol Hill and Pioneer Square startup scenes. It was a clean geographic slate for young companies hoping to write a new story.

Then Amazon started putting up signs. Slowly, pedestrian traffic increased. Parking got tougher. Taco waits got longer. And, eventually, there were police.

The cops were there because of the people, and not because those people were breaking the law. They were a response to the sheer size of the carefully selected and systematically seasoned employee base of Amazon.com. And those employees brought more than just law enforcement; they brought restaurants, parking garages, and an exciting variety of themed food trucks, many of which carry burritos anyway.

Clearly, word got around that South Lake Union was amassing technical talent and optimizing for burritos, because startups moved in en masse. Some were TechStars graduates and some were food trucks, but most were companies established elsewhere in the Seattle area, noticing that the action was moving to South Lake Union.

One such company is Glympse, the location-sharing startup that showed off their new SLU digs last night, hosting the Seattle digerati at their sold-out open house.

“I got in!” I overheard a ticketless young woman say to a friend, as though this were a post-Oscars fete at Kim Kardashian’s Calabasas mansion. “I just acted like I belonged and no one stopped me!”

Or maybe the Kardashian comparison is less apt than, say, a comparison to an invite-only party at a hot Valley startup.

Glympse is certainly hot right now. Last summer, they announced they’d acquired a million users — and promptly closed a $7.5M Series B led by Menlo Ventures and Ignition Partners. They were still operating out of the nondescript back offices of an industrial Redmond complex and about to go on a hiring spree. Their goal? To revolutionize the way smartphone users answer the question “Where are you?”

At some point, they asked themselves the same.

“South Lake Union is the sweet spot of Seattle,” says Glympse CEO Bryan Trussel. “It wasn’t an easy choice to move from Redmond. It certainly wasn’t convenient or cheap. But it took about 2 hours after we actually moved in to know we made the right choice.”

One of the motivating factors behind that “right choice” was Ignition VC Michelle Goldberg, who sits on Glympse’s board and encouraged Trussel to move the company westward, toward Amazon’s new stomping grounds.

“We love being next to Amazon,” says Trussel. “They are to South Lake Union and Seattle what Microsoft was to Redmond and the Eastside in the 90s. They attract a lot of talent. Talent begets talent.”

Glympse wasn’t shy about showing off its own talent for startup interior design at their event. Their roomy new digs boast a Kinect (perhaps a final nod to their Redmond roots), a kitchen with a cereal bar, and an impressive ping-pong table (“It looks Olympic-style,” said my boyfriend.)

The party was catered by – what else? – food trucks, the culinary staple of the area, and now a competitive enough space that ChopStix Mobile jostled to cater the party before its “South Lake Union debut” later this summer.

It’s a far cry from Glympse’s old home, and Trussel says his startup family has adjusted well. “It’s one of my top learnings in this startup journey,” he says. “Even focused, productive, driven people will do significantly better if you pay attention to the surroundings.”

Glympse, like so many Seattle tech startups making the pilgrimage to South Lake Union, is on the hunt for even more of those people.

“There’s a huge concentration of smart, motivated tech folks at the food trucks in our parking lot every day,” says Trussel.

“We set up a guest WiFi for those in need. The public network is named ‘Glympse Is Hiring.’”

Sasha Pasulka is the VP of Marketing at Salad Labs and a digital strategist at Red Magnet Media. You can follow her on Twitter @sashrocks. More from Sasha Pasulka on GeekWire: Hey, startups, users aren’t free…. Why Facebook may surrender users to niche social networks.