Final answer:
The UTM projection would not be suitable for making a map of the contiguous United States. Local and earth-centered datums have different characteristics and uses in mapping.
Step-by-step explanation:
The UTM projection would not be a good choice for making a map of the contiguous United States because it is a global projection and is better suited for larger areas like entire countries or continents. UTM, which stands for Universal Transverse Mercator, is a cylindrical projection that divides the world into 60 zones, each with its own central meridian. This projection is most accurate near the central meridian but becomes increasingly distorted as you move away from it. Since the contiguous United States spans multiple UTM zones, using UTM projection would result in significant distortion in certain areas, especially along the east-west direction.
In contrast to a local datum, which is based on a specific area or region, an earth-centered datum is based on the entire Earth. Local datums are best suited for mapping small areas because they take into account the specific characteristics and conditions of that area. On the other hand, earth-centered datums provide a more consistent and standardized reference system that can be used globally.