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.
Large postcards can measure up to 6 ââ high, 11 Â½â long and Â¼â thick, but they cost as much as a First-Class Letter ($0.47 and up) to send. To qualify for postcard pricing, your mailer must be at least 3 Â½â high, 5â long and 0.007â thick (approximately the thickness of an index card), but no more than 4 Â¼â high, 6â long, or 0.016â thick.