It is perhaps difficult to imagine, but during the United States' early years a policy of nearly open borders prevailed. Immigrants were an important source of labor for a fast-expanding country busy developing and pushing into frontier territory. In the 1860s:

The few immigration-related laws passed prior to the Civil War did little to restrict the flow of immigrants, pertaining instead to naturalization and record-keeping. Although almost a century has passed since the United States first developed a comprehensive immigration policy (as opposed to laws meant only to exclude particular racial or national groups), the idea of the United States as opening a golden door for the world's tired and poor retains a foothold in political and popular discourse.

Moreover, in arguments regarding the ethics of immigration policy, many analysts advocate open borders (Ackerman 1980; Carens 1987; Carens 1992; Cole 2000; Dummett 2001; Lomasky 2001; Pritchett 2006; Wall Street Journal 1984). For example, Michael Dummett argues that: