Final answer:
The two main datums in geodesy are the North American Datum of 1983 (NAD83) and the World Geodetic System of 1984 (WGS84), which provide a reference point for determining latitude, longitude, and elevation coordinates in the United States.
Step-by-step explanation:
The two main datums in geodesy that create the foundation for navigation and transportation in the United States are the North American Datum of 1983 (NAD83) and the World Geodetic System of 1984 (WGS84). These datums provide a reference point for determining latitude, longitude, and elevation coordinates.
NAD83 is primarily used for mapping and land boundary determinations within the United States, while WGS84 is used for global positioning and navigation systems. Both datums are based on a mathematical model of the Earth's shape and provide standardized coordinate systems for accurate location measurement.