Basic to several key issues in current urban economic theory and publi
c policy is a presumption that local imbalances between employment and
residential sites strongly influence people's commuting patterns. We
examine this presumption by finding the commuting pattern for the Los
Angeles region in 1980 which would minimise average commuting time or
distance, given the actual spatial distributions of job and housing lo
cations. We find that the amount of commuting required by these distri
butions is far less than actual commuting, and that variations in requ
ired commuting across job locations only weakly explain variations in
actual commuting. We conclude that other factors must be more importan
t to location decisions than commuting cost, and that policies aimed a
t changing the jobs-housing balance will have only a minor effect on c
ommuting.