Pop quiz: Was the percentage of the U.S. population that is foreign-born higher in 1860, 1880, 1920, or on July 1, 2015? If you answered “2015,” you’re right. The portion of the U.S. population that is foreign-born is now 13.5 percent, surpassing even the tallies for 1860 (13.2 percent), 1880 (13.3 percent), and 1920 (13.2 percent), and fast approaching the all-time record set in 1890 (14.8 percent), according to the U.S. Census Bureau (see here and table 2).

Moreover, the rate of change has been rapid.  In 1970, foreign-born residents made up just 4.7 percent of the U.S. population.  So, in less than 50 years, the percentage of the population that’s foreign-born has nearly tripled—and much of that immigration has been illegal (and hence ill-suited to assimilation).