New Castle Borough municipal offices are located at 230 North Jefferson Street, New Castle PA 16101.
John Carlyle Stewart and his relatives were the first European settlers on land that would become the City of New Castle. They had previously lived near New Castle, Delaware, and after surveying the town site around April of 1798, they named their new community New Castle, Pennsylvania. Their town-plat encompassed about fifty acres and was located at the confluence of the Shenango River and the Neshannock Creek. The North Hill area was not included in the first town-plat, which stops at North Street one street below the southern boundary of the North Hill Historic District. New Castle was the first town to be platted in what is now Lawrence County. The early settlers were predominately of Scottish-Irish descent along with German, English and Welsh inhabitants. The first settlers earned a living as farmers, shoemakers, tanners, hatters, carpenters, stonemasons, coach-makers, blacksmiths, wheelwrights, cabinet-makers, tavern keepers, and merchants. The community grew slowly but steadily. New Castle achieved the status of becoming a borough on March 25, 1825 with less than three hundred inhabitants.
Canals were instrumental in manufacturing growth, thus spurring an increase in population and housing. The completion of the Beaver Extension of the Pennsylvania Canal in 1833 connected Beaver to New Castle. In 1838, the Ohio Division "Cross-Cut" Canal opened, connecting New Castle with a railhead in Youngstown, Ohio and in 1844 the Erie Extension Canal opened. These waterways allowed Lawrence County's large quantities of coal, limestone and iron ore to be shipped to other areas of the country. Prior to street car and railroad transportation, the canals were also a primary means of long distance travel. A dock located on the Neshannock Creek enabled travelers access to the borough of New Castle. Early employers included grist, saw and linseed oil mills, distilleries, tanneries, carding factories, hat, drum, shovel makers, steel wire and nail works. In 1838, James D. White opened the first iron manufacturer, Aetna Iron Works, on the Neshannock Creek, which included a stone blast furnace. The canals provided another vehicle for exporting manufactured goods and led to a greater demand for labor. New Castle's population grew from 611 in 1840 to 1,563 in 1850. Growth in the area resulted in the creation of Lawrence County in March 20, 1849. The Borough of New Castle, formerly part of Mercer County, became the county seat.
In an 1858 speech given in honor of the enlargement of the borough, the Honorable John W. Forney stated the manufacture of iron was the principal business in New Castle. Having all the necessary furnaces, rolling mills and nail factories, the local manufacturers were able to take ore, coal and limestone from the area and create every grade of article, from railroad iron down to three-penny nails.
The canal influence ended with the coming of the railroad and between 1870 to 1890, New Castle became an important rail hub. The railroad in turn aided in further industrial expansion. The industrial boom occurred after The McKinley Tariff Act of 1890 placed a tax on all imported tin plate. This motivated George Greer and local groups of investors to open the New Castle Steel and Tin Plate Company in 1893. "The establishment of this giant industry in New Castle was due in chief measure to the enterprise and personal exertions of Mr. George Greer, the present district manager. The fact that New Castle from 1890 to 1900 increased in population from 11,200 to almost 29,000, and subsequent to that of a city of 40,000 or more, largely due to its tin industries. This enterprise has its origin in 1892, a company being then organized by George Greer; president Charles Greer, secretary, and W.S. Falt as treasurer, for the purpose of erecting a tin plate plant. They first erected a four-mill plant with a bar-mill in connection. The works were put in operation October 26, 1893. This company was known as the New Castle Steel and Tin Plate Company and the mill was sometimes known as "Greer's Tin Mill," Mr. Greer being the leading spirit of the enterprise. In 1897, the Shenango Mill, which is the largest mill of its kind in the world, was erected by certain gentlemen representing the Shenango Valley Steel Company, namely William Patterson, John Stevenson, W.E. Reis and others. Before New Castle's Shenango mill was completed, the works were purchased by the American Tin Plate Company. Mr. Greer, Patterson, Stevenson and Reis all built homes in the district. Another major manufacturing concern was the Pennsylvania Engineering Works Inc. In 1899, the plant manufactured machinery, casting, boilers, blast furnaces, and other steel plant components. The president, Edward King, and vice-president, Edwin N. Ohl, both built homes on The North Hill by 1906. The King mansion is located at 316 Rhodes Place and the Ohl mansion is located at 208 Lincoln Avenue.
In 1901 the Shenango China Company was incorporated and erected a plant in New Castle. The company engaged in the manufacture of semi-vitreous China, both plain and decorative. The president was E.N. Baer, vice-president, Edward Noris, and treasurer, E.E. McGill. Five years later the plant employed over 400 people, some of whom undoubtedly purchased homes on the North Hill which was rapidly expanding. The products they made were shipped all over the world.
By 1906 New Castle began to grow and assert itself as a significant industrial city. Arron L. Hazen in 1906 describes New Castle as follows: "It is chiefly to the extraordinary development of her manufacturing of industries that New Castle owes the great degree of prosperity and fame she now enjoys. The five railway trunk liners joined to give New Castle the distinction of having the heaviest freight traffic of any city of its size in the world. Most of this was the direct result of the phenomenal increase in the extent and importance of her manufacturing interest. Today New Castle manufactories compel the admiration of the world. She has the largest tin plate mills and production of limestone; while the great Carnegie Steel Works operation with four large blast furnaces, the Republic Iron and Steel Company, and the Elliott-Blair Steel Company form another leading factor in her industrial prosperity. In addition to these she is home to factories of window glass, brick, flour, enamel ware, paint, varnish, lumber, cement, and various products of the country, besides other minor industries."
The increased demand for iron, tin and steel during World War I accelerated growth and prosperity in the district. By 1917, there were sixty mills in the city and it was considered the fastest growing city in the nation.