Boundary Street is a three-lane one-way street in Kowloon, Hong Kong. It runs in an easterly direction from its start at the intersection with Tung Chau Street in the west, and ends at its intersection with Prince Edward Road West in the east, near the former Kai Tak Airport.
Historically, the street marked the boundary between the southern part of Kowloon, ceded by Qing China to Great Britain in 1860, and the northern part of Kowloon (New Kowloon), which remained part of China until it was leased as part of the New Territories to the United Kingdom in 1898 for 99 years under the Second Convention of Peking. After the lease, the boundary was renamed from Boundary Line to Old Frontier Line.
The boundary was highlighted by a long line of high bamboo fences, which effectively blocked smuggling between Chinese Kowloon and British Kowloon at that time. The barrier became obsolete when the New Territories joined the colony.
Although the street marks the historical boundary, the road did not come to exist until 1934, more than 30 years after the lease of boundary north. The road was built to accelerate the development of Kowloon Tong and identify the difference in calculation of rates between the boundary north and south.