Michael J. Ferrantino and Aimee Larsen of the USITC write:
The collapse of US housing associated with the financial crisis shows up clearly in US construction imports, which began to decline much earlier than US imports in general and have fallen more deeply. US real imports of sawn or chipped wood, of the type used in construction, peaked in May 2005 and declined by 62.9% through May 2009. This peak is 29 months earlier than the general peak in US imports. The corresponding price series peaked earlier, in March 2005, and has declined by a cumulative 32.5% through May 2009. A simultaneous decline in prices and quantities is a clear indicator of a decline in import demand, induced by the declining demand for construction. Similarly, US real imports of equipment such as bulldozers, graders, and shovel loaders, which have multiple uses but are important for construction, peaked in May 2006, 19 months before the general peak, and declined by 81.5% in the subsequent three years.
Import prices and quantities for inputs related to housing turned down relatively early compared to more direct indicators of the state of the housing market, such as new housing starts (peaking in May 2005), housing units under construction (September 2005), the Case-Shiller Composite-20 home price index (July 2006), and prices of new one-family homes under construction (March 2007). Construction firms anticipated the bubble, restricting their purchases of imported wood inputs at least as early as their construction activity and well before the decline in housing prices. Since construction plays an important role in the business cycle (Leamer 2007), this suggests that import data on construction inputs may be an important tool in anticipating the business cycle.