I don't know when exactly I started thinking of Beijing as home. But I first noticed it last October, when I went to Seoul for a few days and felt homesick—for Beijing. Flying into Beijing Capital International Airport, taking the Airport Express downtown, felt familiar and comforting. I was returning to my apartment, my job, my life.

Visiting family and friends in the United States, I'd catch myself saying things like, "I'll take care of that when I get home (to China)" or "No, I don't do much cooking at home (in China)." How did noisy, sprawling, unrelenting Beijing become my base of operations?

The biggest factor might be time. I've lived in Beijing for almost three years, which is not long, but for newcomers it's enough to make me an old China hand. When I'm with a group of foreigners, it's not uncommon for me to be the one who's been here the longest.

Beijing changes noticeably from week to week—businesses opening and closing, condos springing up overnight—so to watch it transform over several years has been astonishing. In the past three years, four subway lines, an airport terminal and a railway station have opened. The Beijing Olympics have come and gone. The new CCTV building has gone up and burned down. Every major event or change makes me feel closer to Beijing, part of its history.

But my feeling of home in Beijing also comes from repeating the same tasks and activities year in and year out: searching for an apartment, visiting the visa office, trying to drown out the rapid-gunfire sound of Spring Festival fireworks. Now I can say with authority, "Last year the weather wasn't like this. It's never this cold in April."

It also helps that Beijing offers that rare combination of big-city convenience and small-town feel. I used to live in Tongzhou, which had the small-town feel but was somewhat isolated from downtown Beijing (and even that is changing, now that the local government is developing Tongzhou into a new city center). Living downtown means enjoying the best of both worlds. I can stick to my neighborhood or venture further afield. I like being able to walk from place to place, even if Beijing drivers plow through crosswalks like angry bulls. Growing up, I didn't have this luxury. My hometown is spread out and lacks public transportation, so we have to drive everywhere. I might see someone I know at the grocery store or the mall, but it's not the same as running into someone on the street. It's hard to feel connected to other people. Here I recognize people in my neighborhood or even on the subway.

At some level, it takes a conscious decision to call someplace home. For foreigners who come to China, time often seems to stop. Life is so different it may no longer feel real. They plan to stay for a year, maybe two, open to new experiences but not taking life too seriously. But sooner or later that year abroad has to give way to real life. You either have to move on or make a commitment to stay. It took a while, but I started to put down some roots. Then one day I realized that I feel more settled and have more friends in Beijing than anywhere else in the world.

None of this makes things easier as I prepare to leave. I'm already scheming ways to come back, as I've seen so many others do.

Beijing can be hard to love, particularly when you're sitting in traffic on the Second Ring Road and the smog hangs so low it obscures buildings right in front of you. Beijing doesn't have Shanghai's skyline or New York's Central Park. But it's endlessly fascinating, always challenging, and ultimately rewarding for those who stick it out.

The author is an American living in Beijing