From 1903, when the United States fostered Panama’s independence from Colombia, to the end of 1989, the United States and Panama maintained a special, if unequal, relationship focused on a canal that lay entirely in Panamanian territory, but had been built and remained controlled by the United States. The other prominent factor of Panamanian history—the concentration of wealth and power in the hands of an oligarchy—would also persist into modern times. The long-term interests of the two nations moved progressively further apart until, in 1989, the United States invaded Panama to ensure the security of the canal and to reestablish a democratic government. Trade through the canal continued to grow until by the late-1980s some 12,000 ships passed through it annually. In 1903 it helped create Panama to achieve one purpose, to obtain a canal connecting the Atlantic and Pacific oceans.