 Delaware Route 1 Business (DE 1 Bus.) is a business route of DE 1 that runs through Milford. DE 1 Bus. starts at a partial interchange with DE 1 southeast of Milford in Sussex County, with access to southbound DE 1 and from northbound DE 1. From this interchange, the route heads northwest into Milford as two-lane undivided Rehoboth Boulevard, passing residential subdivisions. The road continues past homes and some businesses, passing to the east of Marshall Millpond before reaching an intersection with DE 36. DE 1 Bus. curves north before it heads northwest into wooded areas and passes over the Mispillion River on a drawbridge, at which point it enters Kent County. The route heads into business areas and crosses DE 14. The road continues past commercial establishments and turns north onto North Walnut Street. DE 1 Bus. passes to the west of Milford High School and heads north to an intersection with US 113, at which point it becomes concurrent with that route on four-lane divided Dupont Boulevard. US 113 and DE 1 Bus. continue north for a short distance and end at which point the road merges onto northbound DE 1 at a partial interchange at the north end of Milford.
