What is measured in feet specifically in the USA?

The State Plane Coordinate System (SPCS) is a set of two-dimensional coordinate systems designed for specific regions of the United States. Each state, or sometimes regions within states, has its own coordinate system tailored to provide accurate land measurements and minimize distortion over limited areas.

In this system, distances are typically measured in feet, making it a standard practice in surveying applications across the country. The SPCS uses a Cartesian coordinate system, which is particularly beneficial for local projects such as land surveys, construction, and any activities requiring precise measurements.

The other options relate to different systems of height measurement, but they do not specifically utilize feet as a standard unit. For instance, geodetic height, geoid height, and ellipsoidal height are measurements that may involve meters or other units typical in geodesy, which aren't standardized in feet as the SPCS is for surveying in the USA.