An eup or ŭp (Korean: 읍) is an administrative unit in both North Korea and South Korea similar to the unit of town. Along with 'myeon', an 'eup' is one of the divisions of a county ('gun'), and of some cities ('si') with a population of less than 500,000. The main town or towns in a county—or the secondary town or towns within a city's territory—are designated as 'eup's. Towns are subdivided into villages ('ri'). In order to form an eup, the minimum population required is 20,000.

Eup (administrative division) - Wikipedia