Complex sentence: The Estacada post office opened in February of 1904 and the city was incorporated in May 1905 as a camp for workers building a hydroelectric dam on the nearby Clackamas River in order to supply Portland with electricity.
Split into simpler sentences: The Estacada post office opened in February of 1904 and the city was incorporated in May 1905. The community formed as a camp for workers building a hydroelectric dam on the nearby Clackamas River that was to supply Portland with electricity.