Generally, the slowest parcel delivery service is the United States Postal Service (USPS), particularly when using their standard "Retail Ground" or "Media Mail" options, which can take significantly longer to deliver compared to services like UPS or FedEx Ground; these slower USPS options are often chosen for their lower cost.
Key points about USPS as the slowest:
Lower price:
USPS prioritizes affordability over speed, making it the cheapest option for many standard deliveries.
Longer delivery times:
Depending on the distance and service used, USPS packages can take several days to a week to arrive.
Media Mail restrictions:
USPS Media Mail, one of their slowest options, has strict limitations on what items can be shipped.