What were the major foreign policy objectives of the United States between 1815 and 1824? In what ways did the transportation revolution...

I will answer the first few questions and leave you to think about the final two. The theme that ties these questions together is the growth of American nationalism following the War of 1812.

The War of 1812, which ended in 1815, caused the United States to develop a new nationalist foreign policy. In addition to acquiring Florida from Spain in 1819 (with the Adams-Onís Treaty), the United States developed the Monroe Doctrine in 1823....

I will answer the first few questions and leave you to think about the final two. The theme that ties these questions together is the growth of American nationalism following the War of 1812.

The War of 1812, which ended in 1815, caused the United States to develop a new nationalist foreign policy. In addition to acquiring Florida from Spain in 1819 (with the Adams-Onís Treaty), the United States developed the Monroe Doctrine in 1823. Formulated from a speech that President Monroe delivered to the Congress during that year, the Monroe Doctrine declared that the United States opposed European colonialism in the Western Hemisphere at a time when many Latin American nations were becoming independent from Portugal and Spain. In return, the U.S. vowed not to interfere in European affairs. This document had a lasting effect on foreign policy and was cited by Presidents such as Kennedy and Reagan well into the next century. 

After the War of 1812, the United States also turned to building a strong economy, part of its nationalist agenda not to be dependent on European nations for imports. The transportation revolution, including the construction of roads, canals, and railroads, helped support the market revolution in which products could be efficiently exchanged between different markets. For example, the Erie Canal helped create a water route between New York City and the Great Lakes and helped bring agricultural products from the Midwest to the Atlantic seaboard. 

During this time, the U.S. Supreme Court under Chief Justice John Marshall handed down decisions that supported a strong federal government. For example, in McCulloch v. Maryland (1819), the court upheld the constitutionality of the Bank of the United States and stated that states could not tax federal institutions such as the bank. These decisions supported the idea of a strong nation.