Korea's population, district by district, updated every month.

Pick a region and four views appear on one page: population by 5-year age group with year-on-year change, population by age and sex, population by single year of age with the share living in one-person households, and how each year of age has changed over the last five years. Choose a province and its cities and counties are drawn alongside it; choose a city and you get its neighbourhoods.

The source is the Ministry of the Interior and Safety's resident registration count, which records Korean nationals by their registered address. It is a de jure count rather than a census estimate, and foreign residents are not included. Korea's local government has three tiers, and the suffix on each name tells you which one you are looking at: -do and -si at the province level, -si, -gun and -gu for cities, counties and districts, and -eup, -myeon and -dong for towns, townships and neighbourhoods. Place names follow the official romanisation, and where districts have been merged, split or renamed we join the series by name so that comparisons with last year and five years ago continue.

Population structure is where any study design begins. Before writing a single question we look at who lives in the area, how many, and what is growing or shrinking. This is the reference we use ourselves, and since the underlying data are public, we publish it as it is. Charts are refreshed at the start of each month with the previous month's figures.

Source: Ministry of the Interior and Safety, Resident Registration Population Statistics · Analysis: Chainjee · Corrections and enquiries: ask@chainjee.com