How does CBP define 'primary' versus 'secondary' barrier, and where on the Smart Wall map are secondary barriers concentrated?
This fact-check may be outdated. Consider refreshing it to get the most current information.
Executive summary
U.S. Customs and Border Protection (CBP) treats a "primary" barrier as the first physical structure a person or vehicle encounters crossing from Mexico into the United States, while a "secondary" barrier is an additional, often parallel or rearward structure placed to create a double‑layer enforcement zone in select locations [1] [2]. CBP’s Smart Wall documentation and recent contract awards show secondary barriers are being added most heavily in Arizona’s Tucson/Yuma/Tucson‑area projects and in discrete segments of Texas and New Mexico tied to specific sector contracts [3] [4] [5].
1. How CBP defines "primary" and "secondary" barriers
CBP (and related GAO reporting that summarizes CBP usage) defines a primary barrier as the initial physical impediment — pedestrian fence, vehicle barrier, or wall — that is encountered moving into the U.S. from the border; secondary barriers are additional structures located behind or otherwise inland of that primary barrier intended to further impede movement [1]. CBP’s Smart Wall framing consistently uses the language of a combined system — primary and secondary steel bollard walls, waterborne barriers, patrol roads and detection technology — describing secondary walls as part of a double‑layer approach in "some cases" to create an enforcement zone [6] [2] [3].
2. What "secondary" means in operational terms on the Smart Wall
Operationally, CBP presents secondary barriers not as a continuous backstop everywhere but as a force multiplier deployed "where operationally appropriate" to backstop a primary bollard line, integrate with cameras, lights, roads and sensors, and create a corridor in which Border Patrol can detect, delay and interdict crossings [2] [3]. Contract notices and CBP releases repeatedly describe these secondary segments as part of the Smart Wall "double layer" that, together with system attributes, is intended to give agents more control of the border [3] [4].
3. Where secondary barriers appear on the Smart Wall map and in contracts
CBP’s interactive Smart Wall map is the definitive public depiction of project types and locations, and the agency’s contracting announcements reveal where substantial secondary‑wall mileage is planned: the Tucson projects explicitly include dozens of miles of secondary wall in the Tucson/Yuma areas (e.g., Tucson 2 and Tucson 1 projects include roughly 19–23 miles of secondary wall in recent awards), while El Paso and other Texas projects include smaller secondary segments (e.g., El Paso 3 includes approximately six miles of secondary wall) [3] [4]. Local reporting on public comment rounds shows CBP planning 222 miles of barrier projects in Southern Arizona across Pima, Yuma, Santa Cruz and Cochise counties — an area where double‑layer designs and secondary walls are explicitly cited [5].
4. Scale and distribution: what the numbers show
CBP’s own tallies and third‑party summaries indicate that, prior to Jan. 20, 2025, roughly 702 miles were classified as primary wall and roughly 75–76 miles as secondary wall; new contracts in 2025 add targeted secondary miles concentrated in project‑level awards rather than as a continuous parallel line nationwide [6] [7] [8]. Recent contract batches announced in 2025 add dozens of additional secondary miles largely tied to Arizona projects and select Texas sector projects, reinforcing the pattern that secondary barriers are concentrated in specific sectors rather than uniformly distributed [3] [4].
5. Caveats, competing viewpoints and data limits
CBP presents the Smart Wall as a combined system; critics and local stakeholders have emphasized ecological and community impacts of double layers and "walled‑in corridors" — concerns surfaced in reporting around public comment processes in Arizona [5]. The interactive map and press releases identify project types and mileages but do not produce a single downloadable dataset that clearly shades every secondary segment at a national scale in one view, so precise mile‑by‑mile concentration beyond the contract announcements and sector summaries requires consulting the live Smart Wall map and project-specific notices for verification [6] [3].