Historically Ambridge owes its existence to the Harmony Society and the American Bridge Company. The Borough was incorporated in 1905 and derived its name from The American Bridge Company which began construction in 1903 of an immense plant for the manufacture of finished iron and steel products.
The town is located on the Ohio River 16.4 miles northeast of Pittsburgh. The history of Ambridge goes back to 1894 when a suit was filed in the circuit court of Western District of Pennsylvania against the Harmony Society. The Commonwealth of Pennsylvania charged that the Society had no clear title to the land they claimed. The suit arose out of sale of land in Harmony and Economy Townships to the Union Land Company in 1894. Upon receiving judgment in the case the Harmony Society was to pay the sum of $15,000 plus court costs and the Commonwealth relinquished any claim to lands owned by the Society except the grounds known as "Old Economy" as seen today. These were to become the property of the state for restoration as a public museum.
In the very early development of the town, 100 families lived in barrack type buildings in the area of the American Bridge Company and as the town developed, these families moved into the town.
The first section of the town extended from the Big Sewickley Creek along Beaver Road to Eighth Street (Bryden Road). Property for this area was placed in the hands of land companies for the purpose of planning the town.
Ambridge grew rapidly in the following decades. In 1900 there were 620 people; 1910, 5,205 and by 1920, 12,730. During the 1940's the population swelled to 2S,000 as a result of many jobs provided by the industries engaged in war work. The growth of adjacent counties drew many people in the 50's and 60's, and today the population of Ambridge is 11300.
Many nationalities comprise the population with about sixty percent of the people being of immigrant extraction. Among the different nationalities, the Slavic people predominate, which includes Polish, Russian, Ukrainians, Croatians, Slovenes and Serbians. There are also a large number of Italians, Germans and Greeks. These different groups have their own churches, clubs and other social activities. There are about twenty churches in the community, many regarded as ethnic parishes.
American Bridge Division of United States Steel Corporation is still the principal employer of residents, though other corporations such as Armco, Bethlehem Steel, Codo Manufacturing and H. H. Robertson, employ significant numbers today.
In 1973 the borough completed the final clearing of blighted areas of the town. New buildings, a community center to accommodate conventions for 1,400 people and banquet facilities for 1,000 persons, a housing development in Borough Park which will include a medical center, and a shopping mall, are being erected. The redevelopment of the town is being guided by an ordinance adopted in December of 1971 creating an Historic District in the Old Economy area to provide for preservation of the architecture of the buildings in the aesthetics of the traditional period.