sentences:  In 1939 the required population density was increased to 2,000 per km², along with the addition of a financial requirement.In 1953 the population density requirement was again raised, to 3,000 per km², before being removed entirely in 2000.For 22 years, from 1972 to 1994, as well as between March and November 1936, there was only one city municipality in Thailand, which is Chiang Mai, as in 1972 Bangkok had been changed from city municipality, to special governed district.