In 1812, two towns, New Haven and Waterford, were incorporated to form Marietta Borough. It is located at a scenic 90° bend in the Susquehanna River and was formerly known as Anderson's Ferry. French traders had arrived in this area in the late 1600s, followed by Scots—Irish settlers in 1719. The main streets of the two towns that were merged did not meet, resulting in the S—Bend at the center of Marietta.The Rivertownes PA USA interpretive panels are made possible through a grant from the Institute of Museum and Library Services (IMLS).
Commerce developed with the completion of the Pennsylvania Canal (1833) and the railroad between Harrisburg and Columbia (1850). Local entrepreneurs developed thriving iron and lumber businesses. Immigrant workers and river men gave the town a reputation for rowdiness that was in contrast to its academic and religious aspects. Fine Federal and Victorian residences were built as well as homes for artisans and laborers. Annexation of areas east and west of the town increased the borough's boundary in the 1970s.
Marietta citizens have served in the Armed Forces in every conflict since the War of 1812. Depressions periodically devastated local commercial and industrial enterprises. Recurrent floods and ice jams sometimes wreaked havoc on the town, especially in 1936 and 1972. Marietta survived and rebuilt. Marietta's original National Historic District was designated in 1978, and with the 1984 boundary increase,
45% of the borough is on the National Register of Historic Places.