From the first recorded population of 20,235 in 1960, Sipalay's population has  increased dramatically by more than 5 percent annually upto 1975. Growth has gradually  tapered off from 1980-1995 and in year2000 a negative population growth was posted.

         The historical growth of population and human settlements in Sipalay may be traced  to significant development activities that created the pull factor for in-migration in various  parts of the City. The first wave of settlements and movements of population from the  post-war era to the 1960s came with the logging operations particularly in the barangay  of Manlucahoc and in the mid-60s in barangay Nabulao. From 1960 to 1970, population  grew by an annual average of about seven percent. The second wave of migration came  about with the opening of the Maricalum Mining Company (MMC) in barangay San Jose  that resulted in another rapid  increase in population by about six percent annually from  1970-1975.