The direction of trend in relative commodity prices has implications for many developing country growth rates. To assess causal underpinnings we create ultra- long aggregate series shaped by common factors. Tests show that series present a downward trend over the entire sample which can be broken into 4 regimes of predominantly increasing decline: 1650-1820, 1821-1872, 1873-1946 and 1947- 2010. We argue factors like technology are commensurate with this structure. Finally, we suggest the trend in economic activity is a proxy for such factors and show a negative relationship between trends in commodity prices and World GDP that helps explain the resource curse
