1. Reasons for the fascination of a land that streches from "sea to sea":
-Land was a symbol of freedom, independence, and stability. It ensured that future generations would also be Americans and own land. The idea of a extensive land that has to be conquered ties as well with the idea of manifest destiny. In the 19th century, manifest destiny was a widely held belief in the United States that its settlers were destined to expand across North America.
-Opportunity from the vast area of land in America attracted millions of people from other countries, who dreamed of economic stability, political/social equality, job opportunities, political/social equality, and most of all, freedom.
2. Out of the 8 territories that were brought under the flag of the United States by 1853, I believe the most important addition was the state of Florida because:
-It settled a standing border dispute between two countries (United States and Spain)
-The addition of Florida was considered a triumph of American diplomacy and the turning point for the adquisition/incorporation of future states.