On the Zipper Merge and Complying in Advance

They’re rebuilding our city’s interstate interchanges, one at a time. And it’s a process.

The center of Sioux Falls is circled by an auxiliary Interstate Highway — I–229 — which connects South Dakota’s two main Interstates (I–29 and I–90). I–229 was originally designed to provide access to the southern and eastern parts of the city directly from the Interstate, and upon completion formed a kind of border to the city itself. But, as the city has grown, the interstate is no longer on the “edge of town.” I–229 is now fully enveloped, like a tree growing around a metal ring.

Because of this, the existing interchanges no longer support the amount of people who live in the area, which has led to a multi-year reimagining of every major interchange along I–229. To those of us who grew up in Sioux Falls, it’s been a frustrating show of progress — each interchange takes a full two years to rebuild. This means for two full years at least ONE of the interchanges is squeezed down to a single lane.

Right now, that single lane is on our drive to work and school. And we’re facing a traffic crisis: no one has the guts to follow through on a zipper merge.

For those not familiar, a zipper merge is a normal thing that people in large cities deal with all the time. When two roads converge, the traffic has to go somewhere. Either one road takes precedence and the other road just waits for an opening, or both roads merge into each other. The second one is a zipper merge, the idea being that each lane take turns merging into the new single lane.

That’s what’s supposed to happen, at least.

On our drive, though, the zipper merge is a kind of challenge. Part of this is self-identification; Sioux Falls has a metro population of nearly 308,000 people — think Boulder, CO, or Duluth, MN — and this leads to a kind of internal confusion where half of the people who live here think we’re a big city (we’re not) an the other half think we’re a small town (we haven’t been in 40 years). And small towns don’t need to zipper merge.

The other part is visibility. Our drive goes down a pretty big hill, and from the top of the hill you can see to the bottom, where we’re asked to merge into a single lane.

This makes people nervous.

This makes people nervous, because no one wants to be the reason that traffic is slowed. No one wants to deal with the anxiety of trying to get into a single lane during rush hour. Which means EVERYONE tries to get into the single lane in advance. Half a block ahead of the merge point. Two blocks ahead of the merge point. Hell, there are people who know which lane to be in and they start in that lane a half-mile in advance.

This is great for us! WE KNOW HOW TO ZIPPER MERGE! We zoom ahead in our single lane all the way to the bottom of the hill, and then merge at the merge point, like we’re supposed to. About one in every 10 cars does this — ONE IN TEN! — but everyone else is making traffic worse, including the people who merged early. Because when you merge a half-mile before the merge point, you’re not being polite. You’re creating a single-lane traffic jam that stretches backwards for blocks, while a perfectly good lane sits empty next to you. You’re turning a system designed to handle rush hour into a parking lot designed to foster guilt.

If this sounds familiar, that’s because this is a classic example of complying in advance. Within certain circles, and especially in the gentle passive aggressive niceness of the Midwest, we assume that getting in the right place as fast as possible is key, even when complying in advance is actively harmful — is actively making everyone’s commute longer.

Now, listen — there are a lot of situations in which complying in advance is helpful. Getting to the airport two hours early for your flight. Arriving at a restaurant before your reservation time. Lining up for a concert before the doors open. These are all situations where the system rewards you for being early, where compliance codes as preparation, especially where your early action doesn’t interfere with anyone else’s ability to participate in the system.

But a zipper merge isn’t a concert. It’s not a reservation. The merge point isn’t the deadline — it’s the mechanism. And when everyone tries to “comply” before the compliance point, the mechanism breaks.

There’s a line between the two, and it’s drawn when thoughtful preparation degrades into fearful self-censorship. When you’re afraid of the reaction to doing the right thing. When you join the dutiful line of cars in one lane because you think you’re supposed to, despite the fact that the system is designed to work better when you all work together.

Yeah, you’re right. This isn’t really about driving. Complying in advance out of fear doesn’t just break traffic systems. It breaks democracies.

When you comply before you’re asked — when you self-censor, when you fall in line before the line is even drawn — you’re not avoiding conflict. You’re teaching power what it can get away with. You’re doing the authoritarian’s work for them. Every book you don’t read because someone might object. Every conversation you don’t have because it might be uncomfortable. Every time you see injustice and stay quiet because speaking up might make you look like the problem — you’re merging a half-mile early. You’re fueling the traffic jam. You’re giving fascism more spaces to grow.

Don’t do that. Don’t merge early. Do it only when you need to, only when it makes sense. Only at the point where it helps all of us, where it strengthens our world. The early mergers in our city think the people who zipper merge correctly are rude and selfish, as if you’re cutting in line. They might honk! They might refuse to let you in! They’re wrong — they’ve convinced themselves that their anxiety and their inability to follow the rules should be everyone else’s problem. And this is exactly how authoritarianism works: it convinces people that those who resist, who insist on doing things the right way, who refuse to comply in advance, are the troublemakers. The real threat.

But we’re not a threat. We’re just using both lanes. We’re just doing the right thing. We’re just doing what the system needs us to do to work.

So every morning, as we drive down that hill, we practice. We stay in our lane all the way to the merge point. We signal. We take our turn. And we accept that some people will be angry about it, will think we’re the problem, will refuse to let us in. Because the alternative — merging early, sitting in that long anxious line, pretending that our fear is politeness — isn’t neutral. It’s not avoiding the problem. It’s making everyone’s commute longer. It’s breaking the system. It’s complying in advance.

And that’s not something any of us can afford to practice right now.