[4] Much of the District's significance relates to the discovery of natural gas in the east central region of Indiana.

Beginning in the late 1880s and lasting for about 15 years, the Gas Boom changed the economy and the appearance of the region.

[13] Surnames of some of the directors of this company can be found on the District's buildings today — Campbell, Smith, Dowell, and Weiler.

[14] Described as the "future metropolis of Eastern Indiana", the city successfully used its railroad facilities and abundant natural gas resource as enticements for manufacturers to locate there, and became a boom town.

[15] Hartford City was not alone with its good fortune — natural gas (and some oil) had also been discovered in adjacent counties.

[10] Over 1,200 people worked in manufacturing in Hartford City in 1902 — and this was in addition to the bankers, merchants, physicians, and lawyers necessary for a growing population.

Buildings in the commercial district surrounding the courthouse square were made of brick and stone instead of wood.

[25] While some of the manufacturing facilities that depended on a low-cost source of fuel were closed after the boom, others remained in the city because they did not have a better alternative.

[26][28] The commercial building at 210 East Washington Street is the District's sole representative of the Art Moderne style of architecture.

[29] Romanesque Revival architecture was very popular in Hartford City, and at least 7 of the District's contributing buildings were built using this style.

[32] The courthouse and Presbyterian Church are outstanding examples of Henry Hobson Richardson's variation in Romanesque Revival style.

A corner tower, arched windows, recessed entrances, steeply pitched roofs, and multiple exterior textures (rustication) are typical of this style of architecture.

[36] The town was platted using the Public Land Survey System typical of Northwest Ordinance communities — with rectangular blocks, and streets running north–south and east–west.

Hartford City's layout of a courthouse surrounded by an open area was a common design in the "Midwest" of the United States.

Two of these buildings, the Blackford County Courthouse and the First Presbyterian Church, are listed in the National Register of Historic Places.

Designed by Arthur LaBelle and Burt L. French (of Marion, Indiana), the courthouse features the Richardsonian Romanesque style of architecture.

The Blackford County Courthouse reflects the wealth of the city during the Gas Boom, and could be considered a monument to that era.

[49] Hartford City's First Presbyterian Church was added to the National Register of Historic Places on June 13, 1986.

[50] The building was designed by local architect Alec Gable, and built in the Richardsonian Romanesque style.

[52] Located at the corner of Franklin and High Streets, the structure features huge stained-glass windows that were installed by local glass workers.

The chapel contains features a pipe organ that was partially funded by a donation made by businessman and philanthropist Andrew Carnegie.

[42] Other properties, in addition to those listed as outstanding or notable, contribute to the Hartford City Courthouse Square Historic District.

First, a number of events influenced the development of the area (Criterion A), most notable the establishment of Hartford City as the county seat, and the Indiana Gas Boom.

In the late 1880s, the Indiana Gas Boom brought major growth and prosperity to the region, resulting in the construction of numerous commercial, retail, and social facilities in the area surrounding the courthouse.