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is a city in Clackamas County, Oregon, United States. The population was 4,519 at the 2000 census.
Happy Valley was originally called Christilla Valley, named after the first residents, Christian and Matilda Deardorff. They arrived in 1851 and claimed on the floor of the valley.
The city was officially incorporated in 1965. It remained a small community until the late 1990s, when urbanization of the surrounding area became inevitable. Happy Valley became one of the fastest-growing cities in Oregon. Portland State University's Population Research Center estimated the population to be 7,275 on July 1, 2005, a 61% increase over the 2000 Census. Due to phenomenal growth, the USPS issued Happy Valley its own Zip code, 97086, effective July 1, 2006. Previously, it shared with other surrounding cities.