Eight years later, in 1890, Navy Captain Alfred Thayer Mahan published his epic work entitled "The Influence of Sea Power upon History, 1660–1783". Thayer's book led to his being consider to be the leading naval theorist of his time. Roosevelt paid very close attention to Mahan's emphasis that only a nation with the world's most powerful fleet could dominate the world's oceans, exert its diplomacy to the fullest, and defend its own borders. Mahan had incorporated some of Roosevelt's ideas in his essays, and the two men engaged in a high level dialogue. Roosevelt used Mahan's ideas as the basis for American naval strategy when he served as assistant secretary of the Navy in 1897-98. When he became president, Roosevelt made building up a world-class fighting fleet a high priority. By 1904, the United States had the fifth largest Navy in the world. By 1907, it had the third largest. He would later send what he called the "Great White Fleet" around the globe in 1908-1909 to make sure all the naval powers understood the United States was now a major player.
An important part of Roosevelt's plan for achieving naval supremacy involved the building of the Panama Canal, not only to open Pacific trade to East Coast cities, but also to enable the newly improved and stronger Navy to move back and forth across the globe. The idea had first been proposed by President Ulysses Grant in his first message to Congress as president in 1869. Plans for a canal had been considered during prior administrations, but were abandoned as being too expensive, or as engineering impossibilities, or both. At the time Panama was part of the South American nation of Columbia. Building the canal and making it available for use by the American fleet was something that the Columbian government was resistant to. Making it happen would require some political scheming on the part of the American president.
In 1903, Roosevelt encouraged the local political class in Panama to form a nation independent from Colombia. He did so after the Columbian government refused to accept the terms proposed by the United States government for the building of a canal across the isthmus of Panama. Roosevelt dispatched navy vessels to the area for the purpose of putting political pressure on the Colombian government. The gesture implied that if Columbia opposed the efforts of the Panamanian rebels to secede, US military might would be available to support the rebels.
The new nation of Panama sold a canal zone to the United States for $10 million and an annual payment that increase each year. Roosevelt believed that it was a bargain. In his opinion, a passage through the Isthmus of Panama was vital to protect American interests and to create a strong and cohesive United States Navy that could easily move warships between the Atlantic and Pacific oceans. The construction of the Panama Canal was completed in 1914. It resulted in increased trade to Central America and to the American West Coast.
In 1904, the US began construction of the canal. On November 9, 1906, with the Panama Canal project finally realized and underway, Theodore Roosevelt became the first US president to make an overseas diplomatic visit while in office. Roosevelt traveled to Panama to inspect construction of the canal. In a letter to his son Ted, Roosevelt described his impressions of the construction project that he was witnessing. He wrote:
"It is a tremendous sight to see the work on the canal going on. From the chief engineer and the chief sanitary officer down to the last arrived machinist or time-keeper, the five thousand Americans at work on the Isthmus seemed to me an exceptionally able, energetic lot, some of them grumbling, of course, but on the whole a mighty good lot of men."
It has been a common theme of many presidencies for the president to travel to a foreign country at a time when things are not going well for his presidency, and this trip was no exception. Roosevelt’s trip to Panama came at a time when things were not going well with the construction and some Americans were considering the project to be folly. The project had suffered many setbacks, including outbreaks of disease among workers and fatal accidents. Roosevelt pushed for better working conditions and improvements in health care for canal workers. According to contemporary reports, worker morale was boosted by the President’s visit. The Panama Canal project was completed eight years later, in 1914.
After his time in Panama, Roosevelt did not come straight home. Instead, he went to the recently acquired territory of Puerto Rico. Roosevelt’s 17-day trip to Panama and Puerto Rico marked the beginning of a new tradition in presidential diplomacy. Future presidents would mimic his example.