Final answer:
The US government agency that undertakes land survey of untitled lands is the United States Geological Survey (USGS). They conduct land surveys to map and document the topography of the country, creating accurate and detailed topographic maps for various purposes.
Step-by-step explanation:
The government agency that undertakes land survey of untitled lands is the United States Geological Survey (USGS).
USGS is a US government agency responsible for providing scientific information about natural hazards, natural resources, ecosystems, and climate and land-use change. One of the key functions of the USGS is to conduct land surveys to map and document the topography of the country.
Land surveys help in identifying and demarcating land boundaries, determining the size and shape of land parcels, and establishing legal claims to unclaimed lands. Through these surveys, the USGS aims to create accurate and detailed topographic maps of the country, which are valuable resources for various purposes such as infrastructure planning, land management, and resource conservation.