High Quality Content by WIKIPEDIA articles! Delaware Route 299 (DE 299) is a state highway in New Castle County, Delaware. It runs 9.77 mi (15.72 km) from Maryland Route 282 (MD 282) at the Maryland border east of Warwick, Maryland to DE 9 in Mathews Corner, passing through Middletown and Odessa. It overlaps US 301 from just east of the Maryland border to the west end of Middletown. It is also concurrent with DE 15 along the eastern part of the US 301 concurrency. The road runs through a mix of suburban development.