What does the U.S. Geological Survey establish as the official datum for land descriptions?

The U.S. Geological Survey establishes the official datum for land descriptions as the mean sea level. This is primarily because mean sea level provides a consistent and universally-recognized baseline from which elevations can be accurately measured. By using this datum, land surveyors can ensure precise calculations for property boundaries, construction projects, and various other applications that require reliable elevation data.

Mean sea level is defined as the average height of the ocean's surface, which is influenced by various factors but remains the most stable reference point available. This allows for uniformity across different regions and facilitates communication and understanding among professionals involved in land use, real estate, and environmental studies.

The other options, such as average land elevation, the highest recorded point, and floodplain level, do not offer the same level of consistency or recognition as a baseline reference for land descriptions. These alternatives may vary significantly depending on geographical location, making them less suitable as an official standard.