conterminous

connecting without a break; within a common boundary

• “the 48 conterminous states”
• “the contiguous 48 states”

having a common boundary or edge; touching

• “abutting lots”
• “adjoining rooms”
• “Rhode Island has two bordering states; Massachusetts and Conncecticut”
• “the side of Germany conterminous with France”
• “Utah and the contiguous state of Idaho”
• “neighboring cities”

of equal extent or scope or duration