National Route 400 is a significant highway in Australia, primarily located in the state of New South Wales. It serves as a major connector between the cities of Sydney and Newcastle, facilitating the movement of goods and people along the eastern coast. The route is part of the broader National Land Transport Network. The highway spans approximately 160 kilometers and features various landscapes, including urban areas, rural regions, and coastal views. It plays a crucial role in regional development and is vital for local economies, providing access to essential services and attractions along the way.