Applicability of the New Rules. The new cargo securement rules apply to the same types of vehicles and cargo as the old rules, covering all cargo-carrying commercial motor vehicles (as defined in 49 CFR 390.5) operated in interstate commerce.
Most commercially-produced postcards measure approximately 4.21 inches by 5.47 inches. Less commonly, smaller postcards are typically 3.5 inches by 5.5 inches, close to the minimum size the USPS allows.
You can check the postal guide below for these requirements. Q: What are the postcard sizes that can be mailed in bulk and those that comply with the mailing regulations? A: All standard postcard sizes, from 4â x 6â up to 6â x 11â (flat or folded to size), can be mailed.