Here’s a party trick for your next commute: watch a UPS truck for a while. Count the left turns. You’ll be waiting a long time.
UPS drivers avoid left turns almost religiously — roughly 90% of their turns are right turns. It’s not a superstition and it’s not a bit. It’s a rule the company has enforced since the 1970s, and today it’s baked into one of the most ambitious route-optimization systems ever built. This is the story of how “just turn right” saves UPS hundreds of millions of dollars a year.
Why left turns are the enemy
In the US, a left turn means crossing oncoming traffic. That means sitting at the light. Sitting at the light means idling. Idling means burning fuel while going nowhere — and in a delivery truck that does it hundreds of times a day, it adds up fast.
Left turns are also just more dangerous. You’re exposed to oncoming cars, you’re making a judgment call under time pressure, and one mistake is a collision. As UPS’s own site puts it: “Left turns mean idling, which increases the time a route takes. Left turns mean going against traffic, which increases exposure to oncoming cars. Right turns are faster. Right turns save fuel” (Route4Me, citing UPS).
Sometime in the 1970s, a UPS engineer put this together and the company adopted a method called loop dispatch: plot deliveries in a big right-turning loop, serve one side of the street on the way out, and the other side on the way back. Simple. Effective. And it worked for decades.
Then they built a brain for it
In 2007, UPS started work on something much bigger: ORION, which stands for On-Road Integrated Optimization and Navigation. The goal was to take the right-turn rule (plus every other variable — delivery time windows, package sizes, traffic, driver habits) and compute the genuinely optimal route for every driver, every day.
The scale is hard to wrap your head around. A driver with ~120 stops has more possible route combinations than there are nanoseconds in Earth’s history. ORION chews through over 250 million address data points and performs tens of thousands of route optimizations per minute (Supply Chain Nuggets). UPS has called it “arguably the world’s largest operations research project.”
It took a decade to get right. “The hardest part was making it think more like a driver and less like a computer,” said Jack Levis, UPS’s senior director of process management (Logistics Middle East). Early versions produced routes that were mathematically perfect and practically absurd — the kind of thing that looks great on a whiteboard and terrible on an actual street.
The payoff
The numbers are ridiculous. UPS’s basic routing discipline was already saving about 85 million miles a year. Layering ORION on top shaved off an additional 100 million miles — roughly 185 million miles a year total. That translates to about 10 million gallons of fuel saved annually and somewhere in the range of $300–400 million a year in fuel, wages, and vehicle costs (MarketRealist).
Oh, and the TV show MythBusters tested the core idea: they drove a route eliminating left turns and found the trip got 30% longer in distance but used 40% less fuel. The math holds.
The 10% exception
It’s not absolute. UPS authorizes left turns about 10% of the time — when avoiding one would add serious distance, like in a quiet residential area where sitting at an empty intersection is sillier than just turning. The rule isn’t “never turn left.” It’s “never turn left unless the math says so.”
What the driver actually sees
For all the algorithmic majesty, the driver’s day starts pretty unglamorously: ORION spits out a stop sequence loaded onto their handheld (the DIAD), and off they go. Drivers can and do override it — construction, a blocked driveway, pure local knowledge. In fact, when ORION first rolled out, plenty of veteran drivers hated it, because the “optimal” route often looked insane to a human brain: skip the house right in front of you, loop around the block, come back later. The algorithm was right on paper. It just took years of tuning before it felt right behind the wheel.
Why this is interesting beyond trucks
The deeper lesson is that ORION didn’t just change routes — it changed the company’s culture from “drivers know best” to “data knows best,” and then had to win the drivers back by making the data think like a driver. The best optimization in the world is useless if the humans executing it roll their eyes and do their own thing.
So next time you’re running errands, try it: plan your loop with right turns. You won’t save $300 million. But you might save some gas, some time, and one very annoying left arrow. Huh, interesting.