Local total fertility rates differ conceptually from the national-level total fertility rate, due to a diverse range of population processes that occur at local levels. This study thus compares the population characteristics of localities with high total fertility rates and of those with low total fertility rates and, with evidence, analyzes why high fertility rates in many localities in Korea do not lead to high birth numbers or to a population increase. High local total fertility rates are found to have a close bearing on the size, migration and distribution of the female population aged 15~49, while not much correlated with the number of births or a local population increase. Local total fertility rates have been used widely, regarded as indicators that have closely to do with natural population changes and as outcome indicators of locallevel population policies. The findings of this study suggest that there is a need to further consider whether it is valid to use local total fertility rates in the way they have been used. The total fertility rate, defined in short as the average number of children women would have during their childbearing years (15~49 years of age), is also calculated as the sum of age-specific fertility rates. Localities in Korea over the years saw a continued decline in their median total fertility rate within the range of 1~2, in slightly varying degrees, with the magnitudes of the variations remaining largely constant. A point worthy of attention here is that time and again there have occurred upper outliers in the distribution of total fertility across the observed years. To look at the characteristics of localities where those upper outliers occur can be meaningful as it is in a way an exploration of factors to which local fertility differentials are attributed.
