The Trump Administration is frustrated that illegal border crossing attempts, while much lower than in the 1990 – 2008 period, appear to be higher in 2018 than they have since 2012.
Apprehensions along the Mexican border are thought to reflect the total numbers of persons trying to cross the border illegally. There have been estimates that apprehensions are roughly half of the number of people attempt to cross illegally. Between 2012 and 2015, Border Patrol apprehensions along the Mexican border in October were around 30,000. In 2016, they rose to 40,000, apparently due to attempting to cross before the Trump Administration came to power. They dropped back to the 30,000 level in 2017, but now in October 2018 were about 51,000, the highest since 2012.
Pew Research estimates that There was an average of 386,000 annual arrivals of unauthorized persons for the 2011-16 period, compared with 715,000 for the 2002-07 period. That amounts to a 46% decline. (Source here).
The percentage of apprehensions involving families rather than single adults rose from 3.6% in 2013 to 24.9? in 2017. (Source here).
Another category are inadmissables – persons presenting themselves at legal ports of entry but being denied entry. The October 2018 number was about 7,500, which is consistent with past years.