In a land area of 1,099 square kilometers, the diocesan territory covers Incheon Metropolitan City and four areas including Bucheon-si (city), Gimpo-si, part of Siheung-si, and part of Ansan-si in Gyeonggi-do. Some of them are western coastal islands but the majority of the Catholic population lives in the urbanized Incheon and Bucheon areas. During the 1960s and 1980s, it was the second largest industrial area in the country with many large and small factories. It has now become a commercial and residential community as the factories moved out.
In Incheon diocesan jurisdiction, the population is 4,309,664 at the end of 2009. (Some 8.5 percent of the whole population 50,643,781 in the country) Most residents are ethnic Koreans.
One railway and two highways connect the Incheon area to Seoul. It also has its own local subway system. Its harbor is the second largest port in the country, and the international airport is located in Incheon. The major products manufactured are automobiles, and shipping and electronic items. There are many national and local TV and radio stations. Most families have telephone and high-speed Internet connections and most individuals own mobile phones.