Wage war

ILLEGAL immigration from Mexico is not quite a century old. A law of 1917 was the first to regulate the southern border. Stricter controls gradually followed all through the 20th century, often during the low points of a recurring cycle of sentiment towards immigrants. Economic booms have lured workers across the Rio Grande, encouraged by American firms. Downturns have led to demonisation of “wetbacks”. The 1930s and 1950s both saw indiscriminate mass-deportations; in 1976 President Gerald Ford wondered how best to “get rid of those six to eight million aliens who are interfering with our economic prosperity”.

The latest bout of Trumpian immigrant-bashing fits the mould in one respect: it comes on the heels of an economic downturn. But it is also strange, because the undocumented population levelled off after 2007. In 2015 there were just 188,000 apprehensions of Mexicans at the border, down from 1.6m in 2000 (see chart). This is partly because the recession reduced the magnetism of America’s labour market. But it also reflects a much more secure border—the number of border agents quintupled between 1992 and 2010—and changing demography in Mexico, where the birth rate has been falling since the early 1970s.