Final answer:
The coastal plain on the inland of Massachusetts has an average width of 30 miles. It stretches from Cape Cod to the north and gradually rises into the New England upland towards the western side of the state.
Step-by-step explanation:
The coastal plain on the inland of Massachusetts has an average width of 30 miles. This coastal plain is located along the eastern border of the state and stretches from Cape Cod to the north. The plain gradually rises into the New England upland towards the western side of the state.