The problem with the way they estimate border crossers is that they have a doctrinal assumption that they only catch 10% of the crossers. So if something happens that causes them to catch twice as many they assume that means twice as many people tried to cross. The entire illegal alien guesstimation system is built around this presumption that the effectiveness of the border never changes. There's a similar built in assumption when they start talking about the amount of drugs that come over the border. It's a great way to get increased federal funds because no matter how well they do their stats will always say they're no where near controlling the problem.
If they only catch 10% and they caught roughly a million crossers last year, does that means 10,000,000 are actually crossing? And 9,000,000 per year are not apprehended? I don't think so.
Incorrect.
The estimates are actually based on pretty hard data, ranging from electronics to visual confirmation.
On some days we may catch 70%, while on others we may only get 10% or less.
The Agents on the ground know how many get through. We used to keep track, but management and Washington saw the astronomical numbers and nixed that record keeping.