In addition, our results showed that the effects of socioeconomic
factors on urban expansion varied over time. Distance to the city
center and the county center showed consistently negative effects
on urban expansion in the past forty years. The effects of the
distance to roads, however, varied over time. The effects of the
distance to roads on urban expansion became significant after
1992. This change may have been due to the implementation of the
land leasing policy, which started in 1992 and allows the paid
transfer of land use rights. Before 1992, land use rights, and thus the
locations of urban expansion, were controlled entirely by the
government. With the implementation of the land leasing policy,
however, decisions about land use were also greatly affected by the
market. Consequently, locations closer to roads were more likely to
be developed