Housing prices, mortgage interest rates and the rising share of capital income in the United States

Piketty (2014) documents how the share of aggregate income going to capital in the United States has risen in the post-war era. Rognlie (2015) has since shown that this is largely due to the housing sector. This paper explores the determinants of the secular rise in the share of housing capital income (or 'rental income') in the US economy. I first decompose the aggregate national accounts by geographic region and also by type of housing. I then exploit variation across US states in factors that could explain housing capital income, such as interest rates, housing prices and income growth. The analysis shows that the long-run increase in the aggregate share of housing capital income is mainly due to higher imputed rental income going to owner-occupiers. I also find evidence that the rise in the share of housing capital income over recent decades reflects a combination of: 1) lower real interest rates; 2) lower consumer price inflation; and 3) constraints on the supply of new housing in some large US cities. In effect, the paper documents that the fall in nominal interest rates over the 1980s and 1990s raised the demand for housing and pushed up housing prices and rents (relative to non-housing prices) in supply-constrained areas. I estimate that the long-term decline in interest rates can explain more than half the increase in the share of nominal income spent on housing since the early 1980s.