What does this number measure?
The length published by the USGS is about 2 335 m. This is a horizontal dimension: it represents neither the dam's height nor its reservoir. Other sources cite the length along the dam's axis, about 2 309 m, according to their convention.
Compare the stated dimensions
The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.
Source and limitations
USGS published length: 2 335 m; some sources distinguish an axis of approximately 2 309 m. Height is not compared here.
Three Gorges Dam: interpreted downstream view with the central spillway, piers and power station buildings. The width between the two marked ends compares the published 2 335 m; water and foreground are excluded. Other dimensions and details are illustrative, with no claim to a photogrammetric reconstruction.