The level of for-hire freight shipments in September measured by the Freight TSI (135.8) was 4.4% below the all-time high level of 142.0 in August 2019 (Table 2A). BTS’ TSI records begin in 2000. See historical TSI data.

The August index remains unchanged from the figure of 134.1 reported in last month’s release. The March index was revised down slightly, and January’s was revised up slightly.

BTS is withholding the scheduled release of the passenger and combined indexes for September. The passenger index for September is a statistical estimate of airline passenger travel and other components based on historical trends up to August 2021. The statistical estimate does not fully account for the rapidly changing impacts of the coronavirus on the historical trend. Air freight for September is also a statistical estimate. Since air freight makes up a smaller part of the freight index, the freight TSI is being released as scheduled with the air freight estimate included. The August passenger and combined indexes are available on the BTS website.

The Freight TSI combines into one index the month-to-month changes in for-hire freight shipments by mode of transportation in tons and ton-miles. The index measures the output of the for-hire freight transportation industry and consists of data from for-hire trucking, rail, inland waterways, pipelines, and air freight. The TSI is seasonally-adjusted to remove regular seasonal movement, which enables month-to-month comparisons.

Analysis: The Freight TSI increased 1.3% in September from August due to seasonally-adjusted increases in rail carloads, trucking, and air freight and decreases in pipeline, water and rail intermodal.

The September increase contrasted with weakness in some other indicators. The Federal Reserve Board Industrial Production (IP) Index declined 1.3% in September, reflecting decreases of 0.7% in manufacturing, 2.3% in mining and 3.6% in utilities. Housing starts were down 1.6%. Personal Income decreased by 1.0%.

The Institute for Supply Management Manufacturing (ISM) index was up 1.2 points to 61.1, indicating accelerating  growth in manufacturing.

Although the September Passenger TSI is being withheld because of the previously cited difficulty of estimating airline passenger travel and other components, the August index is now being released. The index decreased 2.3% from July to August following an increase of 9.7% in July. Seasonally-adjusted, air passenger and transit declined, while rail passenger grew. The Passenger TSI has now exceeded its level in March 2020 —the first month of the pandemic— for three months in a row but has not returned to its pre-pandemic February 2020 level. The Passenger TSI remains below its pre-pandemic level for the 18th consecutive month. 

Trend: The September freight index increase followed four consecutive months of decline. This was the third increase in seven months for a net increase of 1.8% over the seven months since February 2021. The September Freight TSI is at the same level it was in March 2021 and is 8.4% above the pandemic low in April 2020. The index is 4.4% below its record level of 142.0 in August 2019 and has decreased in thirteen of the 25 months since that peak.

The third-quarter TSI’s net decrease of 0.6% was the first quarterly decrease since the second quarter of 2020 and came in the context of continued quarterly GDP growth.

For additional historical data, please visit TSI data.

Index highs and lows: For-hire freight shipments in September 2021 (135.8) were 42.9% higher than the low in April 2009 during that recession (95.0). The September 2021 level was 4.4% below the historic peak reached in August 2019 (142.0).

Year to date: For-hire freight shipments measured by the index were up 0.7% in September compared to the end of 2020 (Table 3).

Long-term trend: For-hire freight shipments are up 10.8% in the five years from September 2016 and are up 21.9% in the 10 years from September 2011 (Table 5). 

Same month of previous year: September 2021 for-hire freight shipments were up 2.4% from September 2020 (Tables 4, 5).

3rd quarter changes: The freight TSI rose 0.7% in the 1st quarter, rose 0.6% in the 2nd quarter, and fell 0.6% in the 3rd quarter (Table 10).  

The TSI has three seasonally adjusted indexes that measure changes from the monthly average of the base year of 2000. The three indexes are freight shipments, passenger travel and a combined measure that merges the freight and passenger indexes. See Seasonally-Adjusted Transportation Data for numbers for individual modes. TSI includes data from 2000 to the present. Release of the October 2021 index is scheduled for December 8, 2021.

Revisions: Monthly data has changed from previous releases due to the use of concurrent seasonal analysis, which results in seasonal analysis factors changing as each month’s data are added.    

BTS research has shown a clear relationship between economic cycles and the Freight and Passenger Transportation Services Indexes. See a study of this relationship using smoothed and detrended TSI data. Researchers who wish to compare TSI over time with other economic indicators, can use the FRED database, which includes freight, passenger and combined TSI, and which makes it possible to easily graph TSI alongside the other series in that database. See TSI data on FRED.  

For charts and discussion on the relationship of the TSI to the economy, see Transportation as an Economic Indicator: Transportation Services Index.

A BTS report explaining the TSI, Transportation Services Index and the Economy, is available for download.

Table 1: Freight Transportation Services Index since March 2021
Percent Change from Previous Month
(Seasonally Adjusted, Monthly Average of 2000 = 100)

SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.
NOTE: Percent changes based on numbers prior to rounding.

Table 1A: Annual High and Low Points in Freight Transportation Services Index, 2009-2021

SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.

Table 2: Freight Transportation Services Index Monthly Changes, 2018-2021
Percent change from previous month

SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.

Table 2A: Freight Transportation Services Index by Month, 2018-2021

SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.

Table 3: Freight Transportation Services Index Year-to-Date Change, 2012-2021
Percent change to September from December of the previous year

SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.

Table 4: Freight Transportation Services Index from Year-to-Year
Percent Change in the September Freight TSI
(Monthly average of 2000 = 100)

SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.
NOTE: Percent changes based on numbers prior to rounding.

Table 5: Freight Transportation Services Index from Previous Years
Percent Change to 2021 (September to September)

SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.

Table 10: Freight Transportation Services Index Change by Quarter, 2012-2021
Percent change from the last month of the previous quarter

 SOURCE: Bureau of Transportation Statistics. See Transportation Services Index for documentation, data and other background information.

Brief Explanation of the TSI           

The Transportation Services Index (TSI) is a measure of the month-to-month changes in the output of services provided by the for-hire transportation industries.  The freight index measure changes in freight shipments while the passenger index measures changes in passenger travel.

The TSI tells us how the output of transportation services has increased or decreased from month to month. The index can be examined together with other economic indicators to produce a better understanding of the current and future course of the economy. For example, movement of the index over time can be compared with other economic measures to understand the relationship of changes in transportation output to changes in Gross Domestic Product (GDP).

The freight transportation index consists of:

• For-hire trucking,
• Railroad freight services (including rail based intermodal shipments such as containers on flat cars),
• Inland waterways transportation,
• Pipeline transportation (including principally petroleum and petroleum products and natural gas), and
• Air freight.

The index does not include international or coastal waterborne movements, private trucking, courier services, or the US Postal Service.

The passenger transportation index consists of:

• Local transit,
• Intercity passenger rail, and
• Passenger air transportation.

The index does not include intercity bus, sightseeing services, ferry services, taxi service, private automobile usage, or bicycling and other non-motorized transportation.

The TSI includes only domestic "for-hire" freight and passenger transportation. For-hire transportation consists of freight or passenger transport services provided by a firm to external customers for a fee. The TSI does not include taxi services, paid ride services in personal motor vehicles (e.g., Uber, Lyft, etc.), intercity bus services, in-house transportation (vehicles owned and operated by private firms for their own use), or noncommercial passenger travel (e.g., trips in the household car).