How many gallons of milk does the average American drink per year?

How to get close to this number

Estimate weekly and multiply. A glass or two most days plus milk in coffee and cereal is somewhere around a litre or two a week, which over a year gives tens of gallons. Converting from the weekly habit is more reliable than trying to recall an annual total.

The decline is substantial and the reason is in the explanation: consumption has roughly halved since the 1970s. Fluid milk lost its position as a default beverage to soft drinks, juice and bottled water, and the school and household habits that sustained it weakened at the same time.

The inversion is the genuinely interesting part: total dairy consumption actually rose over the same period. The milk went into cheese, which more than tripled per person — driven substantially by pizza, as the cheese question on this site notes. A category can collapse in one form while the underlying commodity grows, and looking only at the visible product gets the trend exactly backwards.