What an encounter is, and what it is not

Every figure the immigration hub publishes rests on one word, and CBP gives the word a meaning of its own. This is what CBP counts when it counts an encounter, in the publisher's own categories, across the 7,143,058 encounters in the series this site holds.

An encounter is an event

The same person encountered twice in a month is two encounters. There is no person identifier in this file and no way to collapse repeat events into individuals, so nothing here is a count of people, and no arithmetic on it produces one.

That is not a caveat about precision. It is the difference between a measure of how often something was recorded and a measure of how many someones there were, and the two move apart whenever the same person is encountered more than once.

Three things, not one

An apprehension is recorded by the Border Patrol, on the ground between the ports of entry. An inadmissible is recorded by the Office of Field Operations, at a port of entry, where a person presented themselves and was found inadmissible. An expulsion was a removal under the public health authority.

There are three rows rather than six because an encounter type belongs to an authority. There is no such thing as a Title 42 apprehension in this file.

One of the three ended part way through

Title 42 encounters appear in eight months of this series, from October 2022 to May 2023, and none after. The series begins in October 2022, so that first month is where this file starts rather than where the authority did.

This is the reason the hub never adds the two authorities into a single series without saying so. A line drawn through the change is a line through two different things, and it steps for a reason that is not migration. Where a total here spans both, it is named as a total of encounters under either authority, which is a defensible thing to count and a different thing from either one.

Four categories of person, as the publisher defines them

FMUA is a family unit alien and UAC is an unaccompanied alien child; both are defined terms in the collection, and they are kept verbatim rather than translated, because a friendlier word would be our definition rather than CBP's.

Single adults are 65.4% of encounters in the series. Accompanied minors are 0.2%, which is small enough that a chart drawn without a note would appear to omit the category.

What this file cannot tell you

It cannot tell you how many people. It cannot tell you how many entered, because an encounter at a port of entry is a person who presented themselves and an apprehension is a person who was stopped. It cannot tell you where anyone came from or was going: the area of responsibility is where an encounter was recorded. And it cannot tell you why any of these numbers moved, because a monthly count carries no information about what changed around it.

What it can tell you is how much enforcement activity of each named kind was recorded, each month, under which authority. Everything on this hub is built from that and says so.