The city 's growth has reflected the push and pull of many social and economic factors . The total population increased in each census from the city 's founding until 1970 , although varying from rates as high as 165 % to as low as 0 @.@ 2 % . In the 1970 census the population decreased , then slightly increased by 1980 , after which the population slowly declined , increasing again since the turn of the 21st century . Between 1980 and 2000 , the population declined more than 14 % . As of the census of 2000 , the city 's population was 39 @,@ 968 , and the population density was 885 @.@ 9 inhabitants per square mile ( 342 @.@ 0 / km2 ) . In 2008 , the city was the sixth largest in the state . The population increased as of 2010 .