Mobility and affordability in US housing

In the US, affordability is changed by some housing policies that are set nationally and by others set locally, Since interventions tend to change rents and prices from market equilibrium levels, they usually lower the volume of transactions, hence mobility. Upon close examination, however, data from the 25 largest US cities do not support the (negative) association of mobility with intervention as strongly as do data comparing different countries with one another. National intervention affects cities uniformly; and local intervention, while important, is usually outweighed by other factors in the US. What matter most are the economic fortunes of particular industries that spur the growth of some cities and hold back others, The more households proliferate or migrate in, the more will a city develop new neighbourhoods and generate chains of moves or turnover of the entire housing stock. Variations in growth rates thus dominate differences in the degree of intervention as spurs or blocks to mobility.