As Costco's revenue has grown, US pet industry spending has grown with near-perfect correspondence, a correlation of 0.988 that is less a spurious relationship and more an accounting identity: Costco sells pet food, pet toys, and pet beds in bulk, and the pet industry counts those sales. The warehouse club and the pet economy are not separate trends so much as nested ones—the pet spending is partly Costco's revenue in disguise.
Costco revenue grew from about 89 billion to over 242 billion between 2010 and 2023. Pet industry spending grew from about 50 billion to over 136 billion. Both serve the same affluent, suburban household consumer who has a Costco membership and a dog. Costco's Kirkland Signature pet food brand is one of the best-selling pet foods in America, and the store's pet aisle is a significant contributor to both metrics. The correlation is partly real and partly a measurement artifact.
Fourteen years of Costco and pet spending is a correlation that contains actual commercial overlap: the warehouse sells the food, the industry counts the sale, and the chart records both. The membership card is swiped, the dog food is bought, and the correlation is partly just the same purchase appearing in two datasets. The Kirkland brand is real. The spurious part is minimal.
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Want to learn more about why correlations like “Costco annual revenue” vs “US pet industry spending” don't prove causation? Read our guide to statistical thinking.
