Scientists are hard at work recalibrating where and how the nation physically sits on the planet. It’s not shrinkage — it’s “height modernization.”

The grand recalibration, called “height modernization,” is part of a broader effort within the National Oceanic and Atmospheric Administration, or NOAA, to establish more accurately where and how the United States physically sits on the planet. This new National Spatial Reference System, encompassing height, latitude, longitude and time, is expected to be rolled out in late 2022 or 2023, Ms. Blackwell said. It will replace reference systems from the 1980s that are slightly askew, having been derived from calculations that were done before the advent of supercomputers or global navigation satellite systems such as GPS.