Over the past decade, apprehensions¹ at the Mexican border were fairly steady at about 30,000 per month. After Donald Trump became president, apprehensions went down, then up, and then spiked briefly during the “caravan” surge of 2019. However, by the end of 2019 we had returned to about 30,000 apprehensions per month, roughly the same as we had during the 2011-2016 period. In other words, even after everything Trump did at the border—separating children from their parents, keeping asylum seekers from filing claims, building a wall, etc—all he accomplished was to get border crossings back to where they had been when he took office.
¹Apprehensions are generally considered a pretty good proxy for the number of people trying to cross the border illegally.