[tansey]

The fed tracks this data: https://fred.stlouisfed.org/series/APU0000709112

[jeffbee]

A better source is the USDA AMS which surveys the prices of several different milk products in retail outlets in many cities. They do this not only for milk but many common foods. The data goes back decades.

Example report https://mymarketnews.ams.usda.gov/filerepo/sites/default/fil...