Delmar is a town in Sussex County, Delaware, United States, on the Maryland border along the Transpeninsular Line. Its motto is "The Little Town Too Big for One State." The population was 1,597 at the 2010 census, an increase of 13.5% over the previous decade. It is part of the Seaford, Delaware Micropolitan Statistical Area and a suburb of Salisbury, MD. When added with "twin city" Delmar, Maryland, the total population of the town was 4,600 at the 2010 Census.
Delmar is located at 38°27.5′N 75°34.3′W / 38.4583°N 75.5717°W / 38.4583; -75.5717 (38.4589, -75.5716).
According to the United States Census Bureau, the town has a total area of 0.9 square miles (2.4 km²), all of it land.