A revenue ton mile (RTM) is a ton of payload (e.g., freight & express, mail) transported one mile. "Freight & Express" comprises any type of non-mail belly cargo, including proprietary (non-postal) express packages. "Mail" is defined by DOT as that cargo having the imprimatur of a governmental postal service, regardless of its status (e.g., priority, first class, bulk).
ATA Report
ATA tracks monthly cargo RTMs transported in scheduled or nonscheduled (charter) service by 14 U.S. passenger and cargo airlines.* Those interested may purchase carrier-specific monthly traffic reports from ATA Publications. The reports classify traffic by region (Domestic, Atlantic, Latin, Pacific). (Note: These reports are free-of-charge to ATA Member Airlines and ATA Industry Members.) For an annual fee of $200, you'll receive 12 passenger traffic reports and 12 cargo traffic reports with data reflecting participating ATA airlines.
*Alaska, Aloha, AA, CO, Delta, FedEx, Hawaiian, JetBlue, Midwest, NW, Southwest, UA, UPS, US Airways
BTS Report
On approximately the second Thursday of every month, the U.S. Bureau of Transportation Statistics (BTS) updates its Air Freight Summary Data with scheduled and nonscheduled cargo RTMs flown by all U.S. passenger and cargo airlines, as well as cargo tons enplaned. BTS posts data by region in both tabular and graphic formats.