Explain at the differences between pre-1890 and post-1890 american expansion

The pre-1890 expansion period in the US was marked by economic expansion (expansionism) fueled by, industrial growth, demand for fertile land, economic opportunities, and used economic policies after the closure of the revolutionary war  while the post-1890 American expansion (19th C) was marked by imperialism, military expansion and formulation of policies to increase US powers, i.e. US signed a treat with China to gain diplomatic and trade relations resulting in the US taking over the Pacific ports.