James K Polk as a president was considered the most powerful personality as compared to all the other presidents of the United States. As a president, he made a lot of changes and committed himself to the idea of manifest destiny. Polk is well-known for leading the nation for the Mexican-American War. He had accomplished victory over Mexico and as a president he tried his best to significantly increase the overall size of the United States. Polk was considered a well known and most influential president and his accomplishments can be said that despite he was carrying a heavyweight but he always managed to keep up his campaign promises.