[dgoldstein0]

I think it's land and sea borders.

Which would encompass all large coastal cities, the gulf coast and much of Texas/new Mexico /Arizona / socal due to proximity to Mexican border + Chicago/Michigan/etc due to proximity to Canadian border

[esseph]

International airports are a border and fall under CBP. So do "vessels", busses that may move between countries, etc.

> Employees traveling internationally on behalf of an organization must take steps to protect sensitive, confidential, or proprietary data carried on electronic devices. U.S. Customs and Border Protection (CBP) has broad authority to inspect electronic devices—regardless of citizenship—at U.S. airports, land borders, seaports, and preclearance facilities abroad.

https://www.potomaclaw.com/news-Border-Search-Inspection-of-...

It's extremely complicated:

https://cdt.org/insights/no-warrants-and-half-a-dozen-differ...

[ssl-3]

AFAICT, the line is 100 miles from the border as defined as "the edge of the US," not as defined as "100 miles from a foreign country."

This line[1] encompasses places even as far inland as Columbus, Ohio, and Columbus, Georgia, which are good examples of being perhaps least border-feeling, non-coastal cities that I've ever spent time in.

I wouldn't blame anyone for having never visited the grand metropolis of Fort Wayne, Indiana, but that's within 100 miles of the line, too.

Lots of other unlikely cities are this way are this way as well.

[1]: Here's a map on ArcGIS. I only found it; I did not have any part in creating it: https://www.arcgis.com/apps/mapviewer/index.html?webmap=f43e...