Seattle, Washington · Large hub · #14 of 458 by 12-month departing passengers screened
Seattle-Tacoma International Airport (SEA) screened about 20.5 million departing passengers at TSA checkpoints in the 12 months to September 30, 2026, up 1.5% on the prior 12 months. Over the same period, US Customs and Border Protection processed about 3.1 million arriving international passengers there. That ranks SEA 14th of 458 US airports by departing passengers screened in Passenger Index's data.
12 months October 1, 2025 to September 30, 2026 · published figures rounded to 3 significant figures. TSA data covers 351 of the 365 days; the annual figure is scaled to a full year.
| Month | Departing passengers screened (TSA) | International arrivals (CBP) |
|---|---|---|
| September 2026 | 1,801,056 | 267,969 |
| August 2026 | 2,109,825 | 319,608 |
| July 2026 | 2,117,054 | 322,556 |
| June 2026 | 1,983,786 | 273,380 |
| May 2026 | 1,751,689 | 262,800 |
| April 2026 | 1,611,287 | 252,995 |
| March 2026 | 1,514,206 | 236,112 |
| February 2026 | 1,316,789 | 206,277 |
| January 2026 | 1,350,782 | 246,905 |
| December 2025 | 1,663,735 | 227,719 |
| November 2025 | 1,524,294 | 212,245 |
| October 2025 | 1,695,127 | 232,746 |
Exact monthly totals for complete calendar months. A month with too few reported days shows "—". Year-over-year change by month, the latest 7 and 30 days and weekly data are in the paid plans.
| Year | Departing passengers screened (TSA) | YoY | Adj. YoY | International arrivals (CBP) | YoY |
|---|---|---|---|---|---|
| 2025 | 20,160,167 | +1.1% | — | 2,953,881 | +11.2% |
| 2024 | 19,924,449 | +4.7% | — | 2,664,210 | +12.6% |
| 2023 | 19,008,420 | +16.0% | +16.0% | — | n/a |
| 2021 | 12,663,405 | +77.5% | — | — | n/a |
| 2020 | 7,172,502 | -66.8% | -68.1% | — | n/a |
Complete calendar years with a full set of monthly data, as reported by TSA. Year-over-year compares the same dates, using only days reported in both years. Adj. YoY leaves out days with a checkpoint missing from TSA's files; — when none were missing (how).
How these numbers are built and what they do not count →
This page shows 12-month, monthly and annual totals. Premium subscribers get SEA's latest 7- and 30-day passengers with year-over-year change, daily and weekly history back to 2015, the departing and international-arrival series side by side, Airport Data for every US airport, and CSV and Excel downloads - data through October 3, 2026.
Seattle-Tacoma International Airport (SEA) screened about 20.5 million departing passengers at TSA checkpoints in the 12 months to September 30, 2026, up 1.5% on the prior 12 months. Over the same period, US Customs and Border Protection processed about 3.1 million arriving international passengers there. That ranks SEA 14th of 458 US airports by departing passengers screened in Passenger Index's data.
In September 2026, 1,801,056 departing passengers were screened at TSA checkpoints at Seattle-Tacoma International Airport (SEA), according to Passenger Index's compilation of TSA FOIA throughput data. CBP processed 267,969 arriving international passengers there that month.
In the 12 months to September 30, 2026, departing passengers screened at SEA were up 1.5% year over year; CBP international arrivals were +5.6%. Year-over-year compares the same 365 days a year earlier, using only days reported in both years.
SEA is a large hub in Passenger Index's FAA-style classification: it handled 2.3% of national TSA checkpoint throughput in the 12 months to September 30, 2026 (at least 1% is the large hub band). The FAA's official hub classes use calendar-year enplanements, so they can differ slightly.
US Customs and Border Protection processed about 3.1 million arriving international passengers (US citizens and visitors) at SEA in the 12 months to September 30, 2026. Travelers who cleared US immigration abroad at a preclearance airport (for example in Canada, Ireland or the Caribbean) arrive as domestic passengers and are not in this count.
Not from this data. TSA screening does not record where a passenger is flying, and CBP counts international arrivals only, so there is no international-departures figure to subtract. The two series measure opposite directions and are shown side by side, never added.
Airports usually report enplaned plus deplaned passengers, counting every arriving and departing passenger including connections. TSA counts departing passengers once, at screening; arrivals and connecting passengers who stay airside are not screened again, so this measure runs well below airport-reported totals, especially at connecting hubs.
TSA checkpoint throughput by airport from the TSA FOIA reading room and passengers processed from CBP Airport Wait Times, both US federal public-domain data, compiled and validated by Passenger Index. The 12-month headline is rounded to three significant figures; the monthly and annual tables are exact. Passenger Index Premium has the full daily series.
Passenger Index, "Seattle-Tacoma International Airport (SEA) passenger traffic", 12 months to September 30, 2026. https://passengerindex.com/web/airports/sea/