DISCOVER ·
History · All notes →Your GPS Used to Lie to You. On Purpose.
Until May 2000, civilian GPS was deliberately degraded — your position could drift a hundred meters, and that was policy, not a bug. One signature ended it.
For years, if you asked the satellites where you were, they answered with a small lie. Not a malfunction — a policy. The White House described civilian car navigation with an error on the scale of a hundred meters 1. That imprecision was working as intended.
The lie had a name: Selective Availability.
Why the sky was telling fibs
GPS was built by and for the U.S. military, and the military did not love the idea that anyone with a receiver could aim with the same precision as a weapons system. So the public signal was degraded on purpose — an intentional distortion, kept in place for national-security reasons 2. Your car thought you were on the next street over. That was the feature.
The midnight that ended it
On May 1, 2000, President Clinton announced the end of deliberate degradation. The change took effect just after midnight EDT, in the first minutes of May 2 1 2.
The White House expected the change to benefit millions of people and businesses using GPS around the world 1.
What a hundred meters was worth
Receivers people already owned gained roughly an order of magnitude in accuracy, according to the White House 1. The historical government FAQ described basic civilian accuracy after the change as 10–20 meters or better 2. Users did not have to buy a replacement receiver to benefit 2.
A hundred-meter error is the difference between the restaurant and the parking garage across the street. Map matching could hide some of it, but the raw signal was fuzzy 1 — and whole industries have since been built on the assumption that it never came back. Ride-hailing, food delivery, running apps, logisticians tracking a single pallet: all are familiar examples of services that benefit from accessible satellite positioning.
It is one of the rare cases where a technology got dramatically better and the public signal itself stayed free.
Find it in the timeline
May 1, 2000 sits near the end of our Same Years, Different Worlds journey — one screen, one policy decision: GPS signal no longer degraded. Scroll back from there and you pass the telegraph, the light bulb, the first power grid: the whole path it took to get a truth-telling satellite into your pocket.
The next time a map app finds you, remember: one obstacle to ordinary satellite navigation was removed by a policy decision.
The timeline has an English toggle at the top if it opens in Chinese.
About the facts in this article
- What is sourced: the announcement, car-navigation example and expected improvement rest on the White House release 1; the actual switch-off time, existing receiver compatibility and historical accuracy figure rest on GPS.gov 2.
- What is editorial: "the sky was telling fibs", the parking-garage comparison, the map-matching aside, the list of everyday industries and the closing "watching a lie get switched off" are our framing; no source phrases them that way.
- The article distinguishes the announcement (May 1) from the actual switch-off (a few minutes past midnight EDT, entering May 2), because the two dates often get merged in retellings. The accuracy figure comes from the FAQ’s historical account of the change, not from a current measurement.
Sources
- Clinton White House archives (clintonwhitehouse4.archives.gov) — President Clinton: Improving the Civilian Global Positioning System (May 1, 2000) The May 1 announcement, a hundred-meter car-navigation example, an order-of-magnitude improvement, and benefits without additional charges for the change.
- GPS.gov — Selective Availability Explains intentional degradation, the actual switch-off time early on May 2 EDT, and the accuracy improvement described in the historical FAQ.