But as the House risks putting divisions within its own ranks on display and goes head-to-head with the Obama administration, it’s worth asking: How secure are the 2,000 miles that stretch from California to Texas today to begin with?

There’s only one problem — nobody can tell you.

Along the border, there are records and metrics of how many Border Patrol agents are on the clock every year, how many migrants are caught illegally crossing into the United States, and how much money is being spent securing the border, but those numbers give merely a slice of the picture. There is no way to know for sure the answers to the bigger questions: How many individuals cross in total? And, how many of them slip by without detection?