Why did United States business interests favor overseas expansion in the late 1800s?

After the Civil War Americans got busy expanding internally. With the frontier to conquer and virtually unlimited resources, they had little reason to look elsewhere. Americans generally had a high level of disdain for Europe, although wealthy Americans were often educated there and respected European cultural achievements in art, music and literature. Americans also felt secure from external threat because of their geographic isolation between two oceans, which gave them a sense of invulnerability. Until very late in the 19th century Americans remained essentially indifferent to foreign policy and world affairs.

What interests America did have overseas were generally focused in the Pacific and the Caribbean, where trade, transportation and communication issues commanded attention. To the extent that Americans wanted to extend their influence overseas they had two primary goals: pursue favorable trade agreements and alignments and foster the spread of Christian and democratic ideals as they understood them. The isolationism that seemed to work for America began to change late in the century for a variety of reasons. First, the industrial revolution had created challenges that required a broad reassessment of economic policies and conduct. The production of greater quantities of goods, the need for additional sources of raw materials and greater markets-in general the expansive nature of capitalism-all called for Americans to begin to look outward.

America had always been driven by the idea of "manifest destiny," which was at first the idea that the U. S. was to expand over the whole continent of North America, "from the Isthmus of Panama to the Arctic Circle." While Canada and Mexico seemed impervious to further expansion by Americans, at least there had been the rest of the mainland to fill up. With the ending of the frontier and the completion of the settlement of the West the impulse to further expansion spilled out over America's borders.