- Southern Terminus:
- Maryland Avenue (DE 4) in Wilmington
- Northern Terminus:
- Delaware-Pennsylvania state line
- 8.97 miles
- New Castle
DE 100 is a north/south route in New Castle County. The first section, Dupont Road, begins at Maryland Avenue (DE 4) and extends north to Kennett Pike (DE 48). DE 100 is then multiplexed with DE 48 along Kennett Pike for two blocks before turning north onto Montchanin Road, which it follows north to the border with Pennsylvania. At the state line, it turns into Creek Road, an unnumbered road.