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Delta Historic District

Delta Boro, York County, PA

The Delta Historic District was listed on the National Register of Historic Places in 1983. Portions of the content on this web page were adapted from a copy of the original nomination document. []

Delta Historic District consists of a single 1 1/4 mile long road designated as Main Street. This road parallels the SW-NE alignment of a prominent slate ridge which runs north from Maryland and, in York County, terminates in bluffs along the Susquehanna River. Main Street itself is sited on a narrow shelf formed by the contours of the ridge's northern slope. The district portrays the wealth of an isolated "boom town" and its relationship to the slate industry which fostered it. The majority of Delta's streetscape was constructed between 1875 -1895 and it is essentially intact. Along it stands a surprising diversity of architectural forms and well-executed features. Stylistically, the district contains Scots-Irish, Vernacular (3 over 3 bay, central doorway I-house modifications), modified Greek Revival, Italianate, Queen Anne, Romanesque Revival, and Colonial Revival forms. Typically, a Delta building consists of a frame and clapboard structure set upon a coursed slate foundation and topped with a slate shingle roof. It is Delta's unique use of slate for building materials and other construction elements which provides an architectural situation which is rare. The district holds 164 catalogued structures; 80 are significant, 57 are contributing, and 27 are intrusions.

Delta's southern boundary is the Mason-Dixon Line. Scott Creek, a tributary of the Muddy Creek drainage system, rises just south of that point and flows parallel with the slate ridge and with Main Street; it runs approximately 600 feet north of the roadway. At Main Street's lengthwise mid-point, Scott Creek bends 900 to the NW and flows through a shallow defile. That perpendicular alignment developed as an arterial transportation link to the north, becoming Delta's first crossroad and the focal point for the borough's development. The initial village settlement consisted of a cluster of structures in the intersection's immediate vicinity, and, stretching southward, a number of well-spaced dwellings along Main Street's south side.

The region's earliest rural building stock consisted of widely scattered Scots-Irish farm sites constructed in stone and log; their influences upon Delta's cross-road settlement cannot be accurately assessed as most of the borough's pre-1860 structures, deemed expendable, were razed to accommodate construction during the accelerated development of the 1880's. Records from 1844 list only four buildings sited within the present borough limits. As with their rural counterparts, these early dwellings were erratically and widely spaced, most probably because Main Street, itself, was not laid out until 1840. By 1860, the same area included 23 structures.

Delta's few surviving pre-1860 structures are of log and of modest size; they also possess general Scots-Irish proportions and bay placement. Also extant are eleven c. 1850-1875 frame buildings which were modeled after typical log cabin forms. Constructed coevally were three common-bond brick dwellings; these three and four bay structures were more refined than their frame contemporaries, two of them having corbelled brick cornice. Evidence in 1860 and 1876 cartographic sources mark minimal growth during that period.

The borough's major developmental or "boom" period coincides with the rapid growth of the nearby slate industry. As frame and clapboard proved to be a most facile construction medium, it followed that during the town's "boom" (1875-1895), only three non-frame buildings were added along Main Street. Presently, 82% of Main Street's building stock stands in frame and clapboard. An 1888 "View of Delta" depicts that decade as one of most rapid expansion. Many lots were subdivided to allow more building; and Main Street was extended north and south with some evolution of cross streets.

Delta's slate, cut from the local quarries, is the borough's raison d'etre; it is also the borough's ubiquitous, unifying element. Used in great volume, the regularity of its application and the variety of forms in which it was incorporated are both unique and significant. More than 90% of the town's foundations are constructed in slate. The rough coursework and the slate's color variations provide a highly unusual appearance. As roofing tiles were the quarries's main product, almost every Delta structure has a slate roof. This hard and durable material was also used for many of the borough's sidewalks, pathways, steps, revetting walls, and gutters and drains. The local jail, a small building sited to the rear of Main Street, was completely constructed in slate; slate porch and fence posts also exist.

As in other portions of York County, home builders blended selected elements of national styles with the vernacular. Although Greek Revival forms were not common in the county, in Delta, three buildings have the proportions of that style, and 13 structures are aligned with their gable ends to the street. A doorway modification became the borough's most popular Greek Revival element; built with a multi-paned transom and with extremely narrow, recessed side lights and panels, this doorway appears on 23 facades.

Queen Anne and other Victorian elements appear on 13 buildings, some are stylistically quite pure, A bank, constructed in 1894 of rusticated ashlar, is fashioned after the Richardson Romanesque; another bank, constructed in brick, incorporates a York-made cast iron facade. Extant are a handful of large cross-gable residences, usually with fine Queen Anne appointments. Five other homes display the proportions and mass of the Colonial Revival movement. These five stand anomalous: as national styles generally came into the county decades late, these masses, constructed in a most remote area, had practically anticipated the national style - a decidedly unusual occurrence for York County architecture.

Having suffered few intrusions, Main Street retains most of its 1885-1895 appearance. Twentieth-century expansion has been limited to unobstrusive cross streets, the extremities of Main Street, and Chestnut Street, laid out in 1890, is sited so as to avoid negative visual impact. The historic district contains 27 intrusions, most of them benign. The more blatant streetscape disturbances occur where modern functional structures have been injected, these include a large cinder block factory (well set back from the street), two gasoline stations, a cinder block garage, and a cinder block newspaper office. A modern brick fire station is sited in the heart of Main Street's oldest area; it too is set back. The remainder of the intrusions are either dwellings of inharmonious styles (Cape Cods, 1 1/2 story ranchers and one house trailer), or older structures whose facades have been unsympathetically altered into shop fronts or which have been otherwise compromised by modernization.


Delta's Main Street Historic District reflects the community's proximity to, and its association with, York County's slate industry, which thrived during the second half of the 19th century. The district contains a variety of architectural types which depict the area's relative prosperity; it also contains a significant and abundant use of slate as building and paving fabric. Study of this district would lead to a greater understanding of the slate industry's social and cultural ramifications, and to a greater understanding of the slate industry's social and cultural ramifications, and to a greater understanding of Welsh culture in America.

It is primarily significant that Main Street's growth and its subsequent architectural development precisely and chronologically display the rise of the slate industry, the wealth generated by it, and the industry's eventual diminution. As a community founded upon a singular industrial manifestation, Delta is unique within York County: the majority of the town having been constructed within two decades (1875-95), its Main Street district present the county's finest example of a late Victorian "boom town." Given the relative scarcity of regions nationally which have supported slate quarrying activities, Delta's situation, both architecturally and culturally is rare. Within an international geological context, slate deposits of excellent quality are extremely rare. The Ordovician deposits upon which Delta is sited yielded a grade of material once judged to be the finest in the world. (Crystal Palace Exposition, London, 1850 [Behre, 1933 p. 387])

Both these deposits and Delta Borough are sited in York County's most remote region. Throughout the 18th and first half of the 19th centuries, this terrain generally supported only widely scattered subsistence farmsteads. During that period, the Scots-Irish were the region's predominant cultural influence. Settling initially in 1734, they found the rugged topology particularly attractive because its basic inaccessibility helped them maintain their clan systems. Structures extant from the 1740-1840 period display Scots-Irish and vernacular (Folk) influences in various proportions of elemental mixtures. The arrival of the Scots-Irish also marked the beginning of small-scale slate quarrying activities.

During the mid-19th century, the slate industry underwent vast expansion due particularly to a substantial influx of quarry men from North Wales who were assembled specifically for that purpose. This concentrated Welsh enclave soon superseded Scots-Irish cultural influences. Church services and school lessons were heard in Welsh; Welsh customs and festivals were commonly upheld, a few of which linger presently. Typically, the quarry men first resided in close proximity to the slate pits. This precipitated rapid growth in villages such as West Bangor, Slate Hill, and Coulsontown, all of which are situated to Delta's east; and as the industry prospered, it foster a more diverse, sophisticated commercial environment, and it generated a new class of consumers.

The quarry owners, the emergent managerial classes, and the pit supervisors eventually wished to avoid the crowded conditions of the workers' villages and the noise and dirt of the nearby quarry operations. The most obvious choice for relocation was the hamlet of Delta. Founded in 1853, Delta had undergone only minor expansion during the time of the industry's burgeoning. The hamlet offered a few established shops and an ale house, but most importantly, Delta provided a wide, well-sited Main Street upon which only a few scattered dwellings had theretofore been erected. Thus, Main Street was an established, easily accessible locus for development which provided a requisite and desirable exclusiveness.

The rapid development of Main Street is not, in itself, extraordinary. However, the building stock which lines it, and the cultural circumstances which governed their form is quite significant. Main Street's structures stand in contraposition to two axioms of cultural geography:

Being coincident with the "boom" of the slate industry, the majority of Delta building stock was contrived to display the wealth of their owners. The styles, forms, and decorations found throughout reflect nothing of the Welsh presence and very little of the Scots-Irish. Those who built along Main Street completely superseded the ethnicity and heritage of both those cultures. As the Welsh are known as nationalists and traditionalists, this overt denial of material forms presents the basis for a variety of cultural/socio-economic studies. Given the slate industry's decisive influence upon the cultural and social expressions manifest in Delta's architectural appearance, the use of the slate itself, as a building material, is also significant given its unusual effect upon the immediate physical composition of the district. No where else in the county is slate utilized with such uniformity or with such diverse application. Regionally, slate roofs are not uncommon but coursed slate foundations most decidedly are; the district's other structural element executed in slate are also uncommon. Given the slate's availability, its use in Delta is decidedly pragmatic. Even so, this employment of slate is most probably attributable as one of the few structural expressions of the Welsh inhabitation. Within a county context, the situation is unique; within a state and national context, similar situations are rare. (Similar features can be found in less concentration in Cardiff and Whiteford, Maryland and along certain sections of Slate Ridge's southern half. These sections form the lower concentration of the Peach Bottom slate area and deserve the attentions of Maryland authorities.) Main Street's intrusions are scattered and have a minimal effect on the integrity of the district and its visual homogeneity. Many of the intrusions are simply not chronologically compatible structures. These also tend to be set back from the streets and are usually benign; a service garage, cinder block factory, and two gasoline stations are the district's most out of character buildings. The balance of the intrusions are historic structures which have been cosmetically compromised by remodelling and modernization. Fortunately, their numbers are few.

Little has been pursued concerning America's slate industry and the role that the Welsh played in its evolution. Further work should confirm that Delta's Main Street Historic District and its relationship with the slate industry and the Welsh culture holds significance at state, national, and international levels.


Behre Jr., Charles H. Slate in Pennsylvania. Pennsylvania Geological Survey, 4th Series, Bulletin M16, Harrisburg, PA 1932.

Delta Centennial Committee. Delta, Pennsylvania: A Centennial Community, 1980.

Fowler, T. N. View of Delta, Pennsylvania. Morrisville, PA 1888.

Gibson, John. History of York County, Pennsylvania. F. A. Battery Co., Chicago 1886.

Nichols, Beach. Atlas of York County, Pennsylvania. Pomeroy, Whitman and Co. Philadelphia 1876.

Prowell, George R. History of York County, Pennsylvania. J. H. Beers and Co. Chicago 1907.

Shearer, W. O. and Lake, D. J. Map of York County, Pennsylvania. Philadelphia 1860.

Stose, G. W. and Jones, A. I. Geological and Mineral Resources of York County, Pennsylvania. Pennsylvania Geological Survey, 4th Series, Bulletin - C6F, Harrisburg, 1939.

York County Historical Society File #136 - Delta.

Schaefer, Thomas L., Historic York Inc., Delta Historic District, nomination document, 1983, National Park Service, National Register of Historic Places, Washington, D.C.

Street Names
Main Street