Final answer:
The first US moon landings were on the Lunar maria, which are much smoother and less cratered than the lunar highlands, making them more suitable for landing.
Step-by-step explanation:
The first US moon landings were on the Lunar maria. The Lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They are much less cratered than the highlands, which are the lighter, heavily cratered regions that are several kilometers higher than the maria. The Lunar maria cover about 17% of the Moon's surface, mostly on the near side that is always facing Earth. This is where Apollo missions, such as Apollo 11, made their historic landings.
The lunar highlands are made of relatively low-density rock that solidified on the cooling Moon and are heavily cratered due to their ancient formation between 4.1 and 4.4 billion years ago. Although the highlands cover a larger portion of the Moon's surface, the chosen landing sites for the moon landings were chosen on the Lunar maria for several reasons, one being the smoother surface compared to the rugged highlands.