As we blogged about earlier, we have been seeing more delays with USPS this summer, but we haven't done a proper analysis of the data.
We thank the shipping company Shippo, who creates prepaid shipping labels for many internet businesses, for just pubilshing a detailed report with statistically significant data on USPS delivery times.
They show that average times got notably longer in July, and here's their graph showing the percent of shipments delayed shot way up in July.
What has really irked us is the problems with the 99th percentile - we're seeing around 1-in-100 shipments super-delayed, and around 1-in-1000 shipments taking over a month to arrive.