In operation from 1910 to 1940 , Angel Island Immigration Station offers the earliest set of parameters. However, in order to understand what happened during the first half of the 20th century, you need to take into account events of the latter half of the 19th century.

The Opium Wars in the mid-19th century between China and Great Britain were emblematic to the type of aggression Asia witnessed from European colonial interests. Meanwhile U.S. Commodore Matthew Perry's storming of Edo Bay introduced American Pacific expansionist interests, while the Mexican-American War concluded its domestic continental growth. World War I was the first clash between a dominant colonial imperialism and nascent independence and democracy movements. World War II pulled the seemingly disparate strands of global events together, after which it could be said that the world realized a new set of principles ought to shape the course of world events.

Educators can use these timelines as an exploratory experience. Comparing events and occurrences at each level -- global events to changes in U.S. immigration policy, events in Asia to events in California, and so on -- allows students to see patterns of cause and effect , to see that global events, political turmoil and foreign policy negotiations are all tightly intertwined with the flow of immigrants who have found their way to American shores.

The waves of newcomers followed the push and pull of historical forces on both sides of the Pacific Ocean -- the lure of economic and political incentives as well as the U.S. domestic reactions to these trends. Moreover, the various iterations of the United States' immigration policy fully reflect those external happenings.