This paper explores the question to what extent non-domestic factors provide an explanation of US inflation over the last three decades. Are lagged dependent variables – traditionally interpreted as proxies for inflation expectations – simply proxies for oil and commodity prices? The results of a Phillips curve covering the years from the first oil price shock to the year 2014 show that crude oil prices, which basically are world market prices, have exerted a strong influence on inflation, while inflation expectations have played a much feebler role in the inflation process since the "Volcker" disinflation. Over the years the effects of domestic factors, such as the unemployment rate, have weakened.