We derive declining exponential rent and density functions for a monocentri
c city from a new set of assumptions, which place restrictions on commuting
costs rather than on the demand for land. The utility function is Cobb-Dou
glas with unrestricted income expenditure shares for land and for the numer
aire good. The marginal commuting cost is assumed to be proportional to inc
ome-earning potential and exponentially declining in distance from the cent
er at a particular constant rate. These assumptions capture realistic prope
rties of congested cities. Under these assumptions, equilibrium land rent,
residential density, and numeraire consumption all decline exponentially wi
th distance, although at different rates. IE it is also assumed that traffi
c speed at the edge of a city is equal to free-flow speed, then the rates o
f decline in rent, residential density, and numeraire consumption all incre
ase with the city's physical size. We also suggest a new statistical proced
ure for estimating negative exponential density functions from a cross sect
ion of cities of various sizes. (C) 2000 Academic Press.