USPS post quarterly delivery statistics. Look under Mailing Services Measurement Results: https://about.usps.com/what/performance/service-performance/ https://

USPS post quarterly delivery statistics. Look under Mailing Services Measurement Results: https://about.usps.com/what/performance/service-performance/ https://about.usps.com/what/performance/service-performance/ Each table for a service type has ~10 years worth of nationwide annual percent on-time delivery. It's harder to compare individual geographic areas (you can change the URL to go back a year or two, not sure where older reports are).