It appears that the American Automobile Labeling Act measures domestic content on a value basis (that is, the amount the manufacturer pays the supplier for it):

It appears that the American Automobile Labeling Act measures domestic content on a value basis (that is, the amount the manufacturer pays the supplier for it): https://www.nhtsa.gov/part-583-american-automobile-labeling-act-reports#:~:text=The%20U.S./Canadian%20content%20(by%20value)%20of%20each%20item%20of%20motor%20vehicle%20equipment%20that%20will%20be%20used%20to%20assemble%20the%20vehicles%20within%20the%20carline; https://www.nhtsa.gov/part-583-american-automobile-labeling-...