How to Read FHWA Traffic Volume Trends — Vehicle Miles Traveled, Seasonal Adjustment and Revisions

As of 13 November 2026, 00:10 KST (retrieved by this page at that time); latest listed on the agency page at retrieval: the Traffic Volume Trends report for August 2026, an 11-page PDF that is the first entry under 2026 on the Federal Highway Administration's Traffic Volume Trends page. The report says it was compiled with data on hand as of October 02, 2026, and all its August data are preliminary. Primary source: https://www.fhwa.dot.gov/policyinformation/travel_monitoring/26augtvt/26augtvt.pdf^[1][4]

Comparison basis: Tables 5 to 7 and the page 2 table are in millions of vehicle-miles and are used as printed; page 1 and Tables 1 and 2 are in billions rounded to one decimal. Changes subtract the displayed values in the same unit, and percentages computed here are rounded to one decimal. The not seasonally adjusted month is compared with the same month a year earlier, as the report does; the July-to-August change in that row is not seasonally adjusted and should not be read as a trend. FHWA's printed seasonally adjusted changes are shown as printed, because the revised July 2026 and August 2025 seasonally adjusted values they rest on are not printed in the reports read here. Note on the year-ago adjusted value: the August 2025 report, as retrieved, prints 276.3 billion miles for August 2025; the +1.1 billion is FHWA's figure, and the revised base behind it is not established.^[1][2]

In three lines

1. Vehicles travelled an estimated 294.1 billion vehicle-miles on all U.S. roads in August 2026 (preliminary), 0.6% less than in August 2025.
2. Seasonally adjusted travel was 278.7 billion miles, which FHWA puts 0.4% above August 2025 and 0.2% above July 2026.
3. Travel from January to August totalled 2,235.5 billion vehicle-miles, up 0.5%.^[1]

A percent change applied to a base. Counts from continuous counting stations give the change from the same month a year earlier: "This percent change is applied to the travel for the same month of the previous year to obtain an estimate of travel for the current month." The base comes from the Highway Performance Monitoring System; the August 2026 report says all vehicle-miles were computed with Highway Statistics 2024 Table VM-2 as a base. The report warns: "Because of the limited sample sizes, caution should be used with these estimates." and adds: "The Highway Performance Monitoring System provides more accurate information on an annual basis." No margin of error is published.^[1][5]

Publication rules. The FAQ says: "The TVT report is produced and released within 60 days after a month's closing." It also says: "Data that covers a minimum of 40 states and 70% of the VMT is required for publication." Missing station data are filled from other road classes in the same state, then from surrounding states, then from national averages for the same road class.^[5]

Seasonal adjustment. "Seasonally adjusted VMT are monthly VMT adjusted to eliminate day of week, weekday and weekend, number days of a month, and holiday effects." The adjusted series is modelled by the Bureau of Transportation Statistics with the Census X13-ARIMA program, and the report notes: "To facilitate historic analysis, the VMT values for the seasonally adjusted series have been updated for the 12 months prior to the current month and in all other months, held at the value from last month's release."^[1][5]

Annual benchmark. The Traffic Volume Trends page says: "Estimates are re-adjusted annually to match the vehicle miles of travel from the Highway Performance Monitoring System and are continually updated with additional data." The FAQ adds: "The December TVT provides the first estimate of annual VMT." That annual figure is preliminary until the HPMS data replace it.^[4][5]

Seasonally adjusted July: 278.1 in July, unprinted in August. The July 2026 report gave 278.1 billion miles for July. The August report puts August at 278.7 and calls it +0.5 billion (+0.2%) over July, while 278.7 minus 278.1 is 0.6. Because the series is updated for the previous 12 months each release, the August report may rest on a revised July value, but it does not print one, so which July value it used is not established.^[1][2]

Seasonally adjusted August 2025: 276.3 in the 2025 report, unprinted in 2026. The August 2025 report, as retrieved, prints 276.3 billion miles. Against that, 278.7 would be 2.4 higher, while the August 2026 report prints +1.1 billion (+0.4%). The revised August 2025 adjusted value is not printed in the reports read here, so the two figures are shown side by side and the size of the revision is not established.^[1][3]

The year-ago month moved. August 2025 not seasonally adjusted travel reads 294,638 million vehicle-miles in the August 2025 report (base: Highway Statistics 2023 Table VM-2), read 295,928 in the July 2026 report and 295,940 in the August 2026 report (base: Highway Statistics 2024 Table VM-2). The August 2026 report states that some historical data were revised based on HPMS and amended TVT data as of December 2024; it does not itemise the changes, so the cause of each revision is not established. Likewise July 2026 moved from 297,771 (preliminary) to 297,770 (revised).^[1][2][3]

How many counting stations. The Traffic Volume Trends page says approximately 5,000, the report's page 2 says over 5,000, and the FAQ says: "There are about 5,500 CCS stations used to collect data that is reported to the FHWA each month." Table 5 of the August 2026 report lists 5,973 stations for August and 5,935 for July. The figures may refer to different counts and dates; the sources do not reconcile them, so this is not established.^[1][4][5]

A third quarter of two months. In Tables 6 and 7 for 2026, the rows labelled Q3 and 2nd Half hold only July and August: 297,770 plus 294,124 gives the printed 591,894, and the -0.2% compares it with July and August 2025 (593,101). They are partial-period totals, not full quarters.^[1]

Regions do not add exactly. The five regional subtotals in Table 5 add to 294,122 against the all-roads total of 294,124; the report notes that system entries may not add to totals due to rounding.^[1]

Regions. Compared with August 2025, travel fell 1.4% in the Northeast, 1.1% in the North Central region, 0.4% in the West, 0.3% in the South Atlantic and 0.1% in the South Gulf (Table 5, preliminary).^[1]

States. By this page's ranking of the 51 rows for the 50 states and the District of Columbia in Table 5, Arkansas shows the largest fall (-3.3%, from 10 stations) and Delaware, the District of Columbia and South Carolina the largest rise (+1.6% each). These are preliminary point estimates with no published error ranges, some from few stations, so small differences between states should not be read as firm orders. The report notes: "Where Number of Stations are shown as dashes, the values for the Vehicle-Miles and Percent Change are derived from the estimated VMT based on data from surrounding States or the nationwide average VMT."^[1]

Against earlier Augusts. In the page 2 table, August 2026 (294,124) is second among Augusts since 2001, below August 2025 (295,940) and above August 2024 (293,332) and August 2019 (293,308), by this page's ranking. Earlier years are restated with each base update: August 2024 read 292,116 in the August 2025 report.^[1][3]

Dates kept apart. Data month: August 2026, preliminary. Data on hand: October 02, 2026 (July report: September 01, 2026; August 2025 report: September 26, 2025). Traffic Volume Trends page: last modified June 22, 2026, although it lists the August 2026 report. FAQ page: last modified January 27, 2023.^{[1][2][3][4][5]}

Next release. The page lists no September 2026 report at retrieval. The FAQ gives the rule of release within 60 days after a month's close and says: "The next month's TVT report will include an update for states that resubmitted or updated their CCS data." No date for the September 2026 report is given, so the exact next release date is not established. The report states: "Revised values for the previous month are shown in Tables 1 and 2."^[1][4][5]