Uncle Sam is looking forward at the prospects of American Nationalism. At the time of depiction, the US had already acquired various territories, depicted by St Thomas and St John islands. Uncle Sam is sitting atop the newly acquired territory and preparing for the new horizons ahead.
To describe American nationalism, the artist depicts Uncle Sam as stoic and dedicated, it is a reflection of how the power and might of the United States was feared by many. The artist also uses the clouds/haze to make the path ahead unclear, which is an accurate representation of how at the time, nobody knew what lay ahead for American nationalism.