What sections of the U.S. southern border wall were built under the Trump, Biden, and prior administrations and how do they differ?
Executive summary
The Smart Wall map and CBP summary list the existing barrier prior to January 20, 2025 as about 702 miles of “primary” barrier and roughly 76 miles of secondary barrier, made up of different fence and wall types (CBP) [1]. Trump’s first administration is credited with building hundreds of miles of barrier—often replacement or upgraded fencing—with widely cited figures around 450 miles constructed during his term (PolitiFact) while earlier pre‑Trump totals were roughly 654 miles of various barriers (BBC) [2] [3].
1. What “miles” mean on the map — one measurement, many types
When officials report mileage they are aggregating multiple barrier types into “primary” and “secondary” counts rather than one uniform concrete wall: CBP’s Smart Wall map groups pre‑January 20, 2025 barrier inventory as ~702 miles of primary and ~76 miles of secondary barrier and explicitly says this is a combination of different barrier types previously constructed [1]. That means mileages reported by agencies or advocates do not indicate a single, continuous design or height but a patchwork of bollard walls, vehicle fencing, pedestrian fencing and other installations [1].
2. Pre‑Trump baseline and what Trump’s first term added
Before Trump’s 2017 inauguration there were commonly reported totals of about 654 miles of barrier on the U.S.–Mexico border — a mix of pedestrian and anti‑vehicle fencing installed over prior years (BBC) [3]. The Trump administration subsequently built or replaced large stretches of barrier; independent trackers and fact‑checks note “hundreds of miles” completed by 2020, with one summary saying ~450 miles associated with his first term while much of that replaced or upgraded existing fencing rather than entirely new corridor coverage (PolitiFact; BBC) [2] [3]. The Government Accountability Office (GAO) documents that Congress appropriated funds through FY2018–2021 for barrier work and that a January 2021 proclamation paused new construction to the extent permitted by law [4].
3. Biden administration actions and the pause‑then‑restart narrative
The Biden administration halted new wall construction upon taking office in January 2021 via a proclamation to pause obligations for wall construction funds, but did not instantly erase previously appropriated funds; GAO reported DHS still had funds and was selecting projects per an amended Border Wall Plan through at least 2024 [4]. Some construction and project selection continued under Biden, and reporting notes announcements of specific miles resumed or planned during his term — for example, reporting of 40 miles of construction announced November 5, 2024 (Wildlands Network) [5]. CBP’s own public map distinguishes barriers constructed prior to January 20, 2025 from projects planned or started since then, indicating the Biden period included targeted contracts and some completed segments [1].
4. Design and policy differences across administrations
Differences are both technical and legal: the Smart Wall concept advanced in 2025 under later Trump orders emphasizes a steel bollard wall or waterborne barriers integrated with roads, sensors, cameras and lighting and explicitly uses waiver authority to bypass certain environmental laws (CBP FAQ) [6]. Earlier Trump projects emphasized rapid construction under emergency authorities and reallocation of funds, producing long runs of tall steel bollards and replacements (PolitiFact; GAO) [2] [4]. Biden’s pause and project selection approach relied more on vetting projects and legal constraints, though he also authorized targeted construction later in his term [4] [5]. Exact design (bollard height, secondary barriers, roads and technology layers) varies by project and is specified on project‑by‑project bases in CBP materials [1] [6].
5. State and local efforts complicate the map
Texas and other state programs built separate stretches of barriers; for example, Texas reported dozens of miles completed under a state program (Texas Facilities Commission) and the state‑led work is tracked separately from federal CBP/ DHS projects [7] [8]. These state projects add to the overall patchwork but are not always counted identically in federal tallies [7] [8].
6. Recent and post‑2025 developments and uncertainties
After January 20, 2025, the incoming administration immediately prioritized new funding and project starts: CBP announced contracts for new miles in Hidalgo and Santa Cruz counties funded with earlier FY2021 funds and subsequent major funding measures (One Big Beautiful Bill) allocated tens of billions for Smart Wall construction [9] [6]. Reporting notes CBP initiated more than 80 miles of new permanent barrier projects since January 20, 2025 and described dozens more in planning (PolitiFact; White House) [2] [10]. Precise completed mileage and the breakdown of which segments were “new” vs replacements continue to change with contracts, and CBP’s Smart Wall map is the primary agency source for up‑to‑date project status [1].
Limitations and competing perspectives: available sources document aggregate mileages and different executive policies but do not provide a single, authoritative annotated map listing which exact miles were built under each individual administration; CBP’s Smart Wall map is the best public tracker for project‑level status [1]. Conservation groups emphasize large ecological impacts of recent construction and count Biden‑era announcements as new miles in 2024–2025 [5]. Federal auditors note legal and funding complexities that affected when and how miles were obligated and built [4].