The Park Blocks' is a linear series of blocks that were intended to be kept as a continuous "green belt" park system by the early town founders. Land deals saw some of the parcels go to private developers, but the system still contains about 19 blocks of green space, and serves as the campus core of Portland State University.
O'Bryant Square and Director Park both occupy isolated blocks originally set aside for green space. The South Park Blocks begin at SW Salmon and form the wooded core of Portland's "cultural district" and the center of PSU. The southernmost two blocks were destroyed for the construction of the I-405 circa 1967.