In 2026, USPS First-Class Mail typically takes between 1 and 5 business days for delivery within the United States. The specific timeframe depends heavily on the distance between the origin and the destination; a local letter within the same city may arrive in just 1 or 2 days, while a transcontinental piece of mail (e.g., New York to Los Angeles) usually takes the full 4 to 5 days. For small packages, the USPS Ground Advantage service (which replaced First-Class Package Service) maintains a similar 2-to-5-day window. It is important to remember that these are "service goals" rather than guarantees. During peak holiday seasons or severe weather events, delivery can lean toward the longer end of the spectrum. For those needing a guarantee, Priority Mail Express remains the only domestic option that offers a 1-to-2-day money-back guarantee regardless of the geographic distance.