How many miles of new border barriers were built between 2017 and 2025 and how many replaced existing fencing?
Executive summary
U.S. agencies report roughly 458 miles of barrier panels were installed from January 2017 through January 2021, and most—about 81% of that mileage—replaced existing fencing (i.e., roughly 371 of 458 miles were replacement) [1]. Federal and CBP statements after 2021 describe additional projects initiated or funded through 2025 — CBP cites roughly 509 miles “constructed” since January 2017 in one release and says it initiated more than 80 miles of new projects in 2025 — but those later tallies mix new construction, replacements and planned projects, and CBP’s public accounting and GAO’s audit use different baselines and time windows [2] [3] [1].
1. What the audited federal number shows: 2017–Jan 2021 — most work was replacement
The Government Accountability Office (GAO) reports that DHS/CBP and DOD installed about 458 miles of border barrier panels across the southwest border from January 2017 through January 2021, and that 81% of those miles replaced existing barriers rather than creating entirely new miles of barrier (about 371 miles replacement, 87 miles new) [1]. This GAO figure is an audit-based summary and is the clearest accounting in the public record for that four‑year period [1].
2. CBP’s own tallies: a higher “constructed” number that mixes project types
CBP public statements list different totals. One CBP release says “approximately 509 miles” of new border wall system were funded/constructed since January 2017 (a figure the agency ties to roughly $9.8 billion in funding) [2]. CBP’s “Smart Wall” materials and news releases after January 2025 describe tens of miles of new contracts and initiatives (for example, 7 miles in Hidalgo County, 27 miles in Santa Cruz County, and contracts/waivers for further miles), and the agency reported initiating “more than 80 miles” of new permanent projects since January 20, 2025 [4] [5] [3]. CBP documents and the Smart Wall map however mix completed, under construction and planned projects and include both new primary barriers and secondary/system attributes, so the 509‑mile figure does not map one‑for‑one to GAO’s audited installation figure [2] [6].
3. Why the numbers differ: definitions, time windows and replacement vs. new
Sources disagree because they use different definitions and time spans. GAO’s 458‑mile figure covers January 2017–January 2021 and counts “installed panels” and distinguishes replacement miles; CBP’s 509‑mile claim and later 2025 announcements cover different timeframes, funding streams, and program names (e.g., “border wall system,” “Smart Wall”) and include projects that replace older, inadequate fencing or add system elements [1] [2] [6]. CBP also reports projects initiated or funded after January 2021 and ongoing obligations through 2025, which GAO’s earlier audit does not include [7] [1].
4. Concrete, attributable tallies found in the record
- GAO (audit): 458 miles installed Jan 2017–Jan 2021; 81% replaced existing barriers (≈371 miles replacement) [1].
- CBP (agency statements): “approximately 509 miles” constructed since Jan 2017 tied to $9.8 billion in funding [2].
- CBP contracts and media since Jan 2025: contract awards include ~7 miles (Hidalgo, Mar 2025), ~27 miles (Santa Cruz, Jun 2025), and the agency says it initiated more than 80 miles of projects since Jan 20, 2025 [5] [4] [3].
5. What’s not settled or not found in current reporting
Available sources do not provide a single, reconciled 2017–2025 figure that clearly separates every mile that was newly constructed from every mile that was replacement across the full period through 2025. GAO gives a clear 2017–2021 audited snapshot with replacement percentage; CBP provides higher numbers that aggregate projects, funding, and planning through 2025 but do not reproduce GAO’s replacement breakdown for the entire 2017–2025 span [1] [2] [7].
6. How to interpret these numbers going forward
Use the GAO 2017–Jan 2021 number (458 miles; 81% replacement) as the strongest audited baseline for that period [1]. Treat CBP’s larger counts (e.g., ~509 miles) and 2025 project announcements as programmatic totals that blend new construction, replacements and planned work and therefore require careful disaggregation before equating “constructed” with “new miles” [2] [3] [6]. Reporters and analysts should ask DHS/CBP for a mile-by-mile, dated inventory that flags whether each segment was new construction, replacement, or a system upgrade to reconcile public claims with GAO’s audit [1] [7].
Sources cited: GAO audit on barrier construction [1]; CBP public statements including “509 miles” and Smart Wall materials [2] [6]; CBP contract notices and 2025 project tallies [5] [4] [3].