Daniel Cauffiel (1867-1930) was a merchant, real estate developer, and entrepreneur of Johnstown, Pennsylvania and Wilmington, Delaware. The Daniel Cauffiel papers depict his career as a small business entrepreneur and as an agent or employee of the du Pont family and in their various businesses.

Gilpin, Van Trump & Montgomery, Inc. provided insurance sales and service to property owners. The business was established in 1865 in Wilmington, Delaware, by businessman James Woolley (1818-1886). By the early-to-mid twentieth century, the company specialized in real estate sales and service, as well as mortgages, becoming Delaware's only full-service real estate organization. The records include minutes, corporate histories, publicity material, as well as information on company properties, and documents the company's rise from a small insurance company to a large, multi-service insurance, real estate, mortgage, and investment firm.

Horace Holden Thayer, Jr. (1878-1959) was a naval architect, mechinical engineer, and businessman. Between 1909 and 1914 Thayer worked for the Delaware Construction Company which was a building company, and a subsidary of the National Real Estate Trust Company, which provided loans and financing for the properties. This small collection consists of papers relating to Thayer's early work with the National Real Estate Trust Company and the Delaware Construction Co. These materials document the formation of the National Real Estate Trust Company and building specifications for the Delaware Construction Co. There is a small amount of papers related to the businesses of his father-in-law Thomas H. Savery (1837-1910), specifically the Harpers Ferry Paper Company and the Shanandeoah Pulp Company.

James W. Flaherty Inc. was a general contractor company in Wilmington, Delaware that operated between 1949 and 1983. Consists of drawings and plans for various local properties, including du Pont family estates.

Peter Arnold Karthaus (1765-1840) immigrated to the United States from Hamburg, Germany in 1796 and established a mercantile business in the West Branch of the Susquehanna River Valley. The collection documents Karthaus' mercantile business, land development in Clearfield County, Pennsylvania, and his partnership with fellow German immigrant, Frederick W. Geissenhainer, a pioneer in using coal to smelt iron.

Sarah A. Evarts (1833-1901) was one of many women who invested in the Woman's Land Syndicate in Chicago. The Syndicate sought a real estate project developed and managed by women, but ultimately failed. The papers consist of brochures, maps, and testimonial letters describing the work of the Syndicate and the prospects and new industries of the adjoining developments of South Waukegan and North Chicago.

The Woodlawn Trustees Inc., a major landowner in suburban Wilmington, Delaware, began developing Woodbrook and Sharpley neighborhoods in the mid-1950s. This collection illustrates the process of creating suburban residential subdivision in the 1950s, 1960s, and 1970s.

The Woodlawn Trustees, Incorporated, is a non-profit real estate development firm incorporated in Delaware on December 12, 1918, by textile manufacturer William Poole Bancroft (1835-1928). Their records include charters, minutes, officer lists, directors' correspondence, real estate records, property maps, reports, drawings and specifications and newspaper and journal articles on the history of the Trustees and of the Bancroft family.

The Woodlawn Trustees, Incorporated, is a non-profit real estate development firm incorporated in Delaware on December 12, 1918, by textile manufacturer William Poole Bancroft (1835-1928). Records consist primarily of 35mm slides, mostly dating from 1989 to 2002, documenting Woodlawn Trustees properties throughout Wilmington and Brandywine Hundred, including low-income city housing, preserved farmland, greenways along the Brandywine Creek, and commercial properties on Concord Pike and the Wilmington waterfront.

The Wurts family were involved in the anthracite coal industry. In 1823 four brothers: Maurice Wurts (1783-1854), William Wurts (1788-1858), Charles Stewart Wurts (1790–1859), and John Wurts (1792-1861) founded the Delaware and Hudson Canal Company originally to mine anthracite coal and transport the resource to New York. The company built the Delaware and Hudson Canal and later became the Delaware and Hudson Railway. The Wurts family papers were collected by John Sparhawk Wurts (1876-1958) and reflect both family papers and business records.