# CBP Bought Online Ad Location Data to Track Phone Locations > Markdown version of an Informer Tech article. Canonical HTML page: https://www.informertech.com/post/cbp-bought-ad-location-data-track-phones > Source: Informer Tech, https://www.informertech.com/ - **Canonical URL:** https://www.informertech.com/post/cbp-bought-ad-location-data-track-phones - **Publisher:** Informer Tech (https://www.informertech.com/) - **Category:** Data Privacy & Protection - **Author:** Tomáš Král - **Published:** 2026-03-07 - **Description:** CBP bought phone location data from ad tech tied to RTB auctions, raising concerns over surveillance, device identifiers, and neighborhood monitoring. --- ## CBP’s Admission: Purchasing Location Data From the Online Advertising Ecosystem United States Customs and Border Protection (CBP) has acknowledged—publicly and explicitly for the first time—that it **purchased phone location data sourced from the online advertising industry**. That acknowledgement appears in a document known as a **Privacy Threshold Analysis**, which was obtained through a Freedom of Information Act request. The document addresses a **trial CBP ran between 2019 and 2021**, and it ties the agency’s access to location information to the commercial ad-tech pipeline—an industry built to target ads, but also capable of supporting surveillance-grade tracking at scale. ### The Privacy Threshold Analysis and the 2019–2021 Trial The key detail isn’t just that CBP got location data. It’s _how_ this came to light: a Privacy Threshold Analysis obtained via FOIA, describing a **time-bounded trial period**. This is important because it shows there’s a formal process inside the organization—something that’s documented, reviewed, and recorded—instead of just a casual or one-off purchase. It also matters because it connects a government agency’s location tracking to commercial data that people generate every day just by using apps and browsing the internet. ## How Real-Time Bidding (RTB) Can Expose Phone Location Data CBP’s purchase is described as involving data **linked to real-time bidding (RTB)**—the behind-the-scenes machinery that decides which ads you see online and in apps. In RTB, ads are often delivered after **automated, instantaneous auctions**, where advertisers bid for the opportunity to show an ad to a specific person. The article describes the darker reality inside the “murkiest parts” of this ecosystem: entities can collect data from your device and package it for sale. ### What RTB Collects: Device Identifiers and Location Signals The advertising industry can collect device-level information, including: - **Phone identifying details** - **Location data** Once collected, that data can be **repackaged and sold** to other companies and entities. In other words, what begins as “ad targeting” infrastructure can become a supply chain for high-resolution tracking. ### Why This Data Is So Valuable for Tracking People The context calls this kind of data a **“gold mine”** because it can be used to track **daily activities**. That phrase is doing a lot of work—and honestly, it should make you pause. “Daily activities” implies routine patterns: where someone sleeps, works, visits, worships, seeks medical care, or meets others. When location data is granular and persistent, it can create a behavioral map of a person’s life—without needing to break into their phone. ## What CBP Won’t Say (and Why That’s Part of the Story) CBP did not respond to a request asking whether it is **still buying** this data. That silence is important. Because the practical question isn’t only _whether_ CBP used ad-tech location data in the past. It’s whether the pipeline remains open today—whether location data drawn from ad auctions is still being treated as something a government agency can simply buy. ## The Wider Pattern: Monitoring Neighborhoods Through Mobile Movement Data The context also points to reported plans involving Immigration and Customs Enforcement (ICE): the agency has reportedly planned to purchase access to a system called **Webloc**, which would allow **whole neighborhoods to be monitored for mobile phone movements**. Even if this is discussed as a separate tool or system, the theme is consistent: **commercial location intelligence** can be repurposed into neighborhood-level visibility—tracking movement not just of individuals, but of populations in a defined area. ## The Surveillance-Heavy Online Advertising Industry as a Data Broker Pipeline The article describes the online advertising world as **sprawling** and **surveillance-heavy**. And that framing matters, because RTB isn’t a niche feature—it’s a core mechanism of how modern advertising works. So you end up with a weird reality: - People think they’re participating in “free content” economics. - But the infrastructure enabling those ads can generate **location traces** and **device-linked data**. - And those traces can be sold onward—potentially to government entities. Not because anyone “hacked” anything. Just because the data exists, is collected, and has a market price.