Research on the spatial expansion history and characteristics of large cities can provide an important reference for the analysis and prediction of urban expansion.This study identifies four phases in the expansion history of Chongqing City and analyzes the urban expansion characteristics at each phase based on literature,maps,and remote sensing images,as well as important events,and urban expansion area and speed.The study shows the following results.Firstly,Chongqing did not expand continuously in history due to major historical events.The city experienced different degrees of shrink in several periods,such as the early stage after it was built,the late Ming and early Qing dynasties,and after the War of Resistance Against Japanese Aggression.Secondly,the driving force for urban expansion of Chongqing was weak before 1891,with an average annual growth rate of merely 0.18%.In addition,urban expansion was closely related to military,and large-scale urban constructions all happened in the regime changing periods.Thirdly,influenced by the events like Chongqing opened as a commercial port and becoming the wartime capital during the War of Resistance Against Japanese Aggression,the city saw a relatively rapid expansion from 1891 to 1949,with an average annual growth rate of 3.86%.However,the poor urban management partly constrained the growth of Chongqing.Fourthly,although the increased urban area of Chongqing was much larger from 1950 to 1996 than that of the preceding two periods,the average annual growth rate was lower than that of the previous period.The constraint of terrain and landform on the city’s expansion weakened gradually.Fifthly,Chongqing has seen an unprecedented expansion since 1997,with an average annual growth rate of 9.69%.After completely breaking through the constraint of hills and rivers,the city tends to sprawl all around.