Immigration histories typically endeavor to describe and hold a nation–state accountable not only for the laws and policies by which it admits some immigrants, but also for those by which it refuses, excludes, or deports other immigrants. This article explores immigration to Mexico and to the United States with attention to its implications for the status of persons, and also for the conventional historical narratives in each country. The article focuses on three techniques of governance that each country has engaged in regard to immigration. These techniques include: 1) the assignment of nationality as a singular attribute of personhood; 2) the use of demonstrable and documentable characteristics as criteria of admission; and 3) centralized registration procedures to monitor and control the immigrant population. The techniques are analyzed together because of their concurrent emergence in each country during the late nineteenth and twentieth centuries. The techniques are also complementary. They form a set that, although not unique to the United States and Mexico, nevertheless illustrates parallels and an interplay between the two countries, and, more broadly, illustrates how immigration presents a common predicament across different times, places, and forms of government.

In 1929, when Lorna Parsons tired of her four-year marriage to a London, Ontario tailor, she decided to seek a divorce—in Reno, Nevada. Even though Lorna's divorce was not generally recognized in Canada, obtaining it was important to her and to the hundreds, if not thousands, of Canadians who similarly sought United States divorces at a time when Canadian law was extremely restrictive. The choices of Parsons and her compatriots should be of interest to legal historians. They problematize the idea of national legal history by reminding us that law does not always remain in the tidy jurisdictional containers constructed by legal authorities and academics. National boundaries are more porous, and the nature of law itself more fluid, than we often admit.