Source: U.S. Bureau of Economic Analysis
Source: U.S. Bureau of the Census
Further information related to the international trade data can be found at https://www.census.gov/foreign-trade/data/index.html
Methodology details can be found at https://www.census.gov/foreign-trade/Press-Release/current_press_release/explain.pdf
U.S. Bureau of Economic Analysis and U.S. Bureau of the Census, U.S. Imports of Services: Transport [ITMTRAM133S], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/ITMTRAM133S, February 19, 2018.