Railroad tracks.
The US standard railroad gauge (distance between the rails) is 4 feet, 8.5 inches. That’s an exceedingly odd number.
Why was that gauge used? Because that’s the way they built them in England, and English expatriates designed the US railroads.
Why did the English build them like that? Because the first rail lines were built by the same people who built the pre-railroad tramways, and that’s the gauge they used.
Why did ‘they’ use that gauge then? Because the people who built the tramways used the same jigs and tools that they had used for building wagons, which used that wheel spacing.
Dispatches From The Front 