Recently arrived Irish immigrants in the the mid-1800s.

Ever since the first Europeans landed here over four centuries ago, America has had a conflicted relationship with its newcomers. It’s a serial drama that continues today in the halls of Congress, as legislators wrestle with a new generation of immigration reform. We are, of course, a nation of immigrants: the U.S. has less than five percent of the world’s population, but is home to about 20 percent of its migrants. And the vast majority of us – everyone, in fact, except for American Indians – can trace our roots to foreign lands. Despite that common thread, though, America has not always treated its newest residents with the most empathy.

There have been four major waves of immigration to America, the last of which – mainly from Mexico and other Latin American countries - continues today. Several themes play out consistently in all four chapters:

• Each successive wave of immigrants has been, to an extent, a reflection of conditions elsewhere in the world.
• Each cycle of newcomers has faced animosity and backlash from the already assimilated.
• The history of America’s immigration policy is one of continual repetition and vacillation, a revolving door that often swings open during periods of economic prosperity and slams shut when times get tough.

Scroll through the timeline below to follow the tangled history of America’s ever-changing immigration policies. The interactive chart beneath it shows rates of legal immigration from 1820 to the present (use the scroll bar to zoom into specific chunks of time).

Number of Foreign-Born Legal Permanent Residents, 1820 to 2012

Source: Department of Homeland Security, Office of Immigration Statistics

View data table