In the law regulating historic districts in the United States, a contributing property or contributing resource is any building, object, or structure which adds to the historical integrity or architectural qualities that make the historic district, listed locally or federally, significant. Government agencies, at the state, national, and local level in the United States, have differing definitions of what constitutes a contributing property but there are common characteristics. Local laws often regulate the changes that can be made to contributing structures within designated historic districts. The first local ordinances dealing with the alteration of buildings within historic districts was in Charleston, South Carolina in 1931.
The Fort Madison Downtown Commercial Historic District has a collection of late-19th century store fronts centered on Ave. G, from 6th to 9th Street, and Ave. H from 7th to 9th, in Fort Madison, Iowa. It was listed on the National Register of Historic Places in 2007.
The Hampton Double Square Historic District is a historic district located in Hampton, Iowa, United States. It has been listed on the National Register of Historic Places since 2003. At the time of its nomination it contained 43 resources, which included 28 contributing buildings, two contributing sites, 10 non-contributing buildings, one non-contributing site, one non-contributing structures, and on non-contributing object. The town of Hampton was laid out by H.P. Allen, who was the county surveyor, in June 1856. The original plat was eight blocks by eight blocks in the shape of an “L”. Near the center of the “L” was the two-block, or double, square. While many county seats in Iowa have a courthouse square, the double square is a rarity. Four double squares were platted in Iowa, but only those in Hampton and Sidney survived their early period of development. Estherville's square was platted as a four-block square, but its development created a double square instead. Hampton has the only symmetrical double square plan in the state. The double square exemplifies the two primary functions of a public square, both commercial and public development.
The Northwood Commercial Historic District encompasses most of the central business district along four blocks of Central Avenue in Northwood, Iowa, United States. It was listed on the National Register of Historic Places in 2006. The historic district includes 59 properties. It includes, as contributing properties, 40 buildings, one site, one structure, and three objects. There are also 14 buildings that are non-contributing.
The Grant Commercial Historic District is a nationally recognized historic district located in Grant, Iowa, United States. It was listed on the National Register of Historic Places in 2002. At the time of its nomination it contained 17 resources, which included 15 contributing buildings, two contributing structures, and one non-contributing building. The historic district covers the town's central business district. Grant is a small town located in northeast Montgomery County in the southwest quadrant of the state. It was plated in 1858, and it was known as Milford until the early 20th century even though its post office was Grant. While not on a railroad, the town was still able to maintain a viable commercial district.
Harlan Courthouse Square Commercial District is a nationally recognized historic district located in Harlan, Iowa, United States. It was listed on the National Register of Historic Places in 1994. At the time of its nomination the district consisted of 54 resources, including 38 contributing buildings, one contributing site, one contributing object, 13 noncontributing buildings, and one noncontributing object. Cross-shaped in plan, the historic district covers most of the city's central business district in the original town plat. Most of the buildings are two-story, brick, commercial buildings. Commercial Italianate and Queen Anne styles are dominant. The Shelby County Courthouse (1893) is a stone Richardsonian Romanesque structure. The courthouse square block and the four surrounding half blocks and rear alleys constitute the contributing site. The Soldier's Monument on the square is the contributing object, and the POW/MIA Monument is the noncontributing object because of its more recent construction.
The Washington Downtown Historic District is a nationally recognized historic district located in Washington, Iowa, United States. It was listed on the National Register of Historic Places in 2013. At the time of its nomination it contained 122 resources, which included 83 contributing buildings, two contributing objects, one contributing site, 34 non-contributing buildings, one non-contributing structure, and one non-contributing object. The historic district is located in the original town plat, and covers the city's central business district. Washington was platted in 1839 as the county seat for Washington County. Central Park, the town square, is the earliest contributing resource having been platted with the original town. It is the contributing site and contains the two contributing objects: the 1931 Civil War monument and the 1939 fountain. The Washington County Courthouse was located here from 1845 to 1869, when it was relocated to its present location a block away. It is one of the contributing buildings. The oldest extant buildings date to the 1850s.
Greenfield Public Square Historic District is a nationally recognized historic district located in Greenfield, Iowa, United States. It was listed on the National Register of Historic Places in 2014. At the time of its nomination the district consisted of 52 resources, including 42 contributing buildings, one contributing site, six noncontributing buildings, and three noncontributing objects. The historic district covers part of the city's central business district in the center of the original town plat. There is a significant number of one- and two-story, brick, commercial buildings, as well as a few three-story structures. The Commercial Italianate style is dominant. While the vast majority of the buildings are commercial buildings, there are four government buildings in the district: the Adair County Courthouse (1892), public library (1916), city hall (1930), and the municipal light plant (1940). Besides the courthouse, the other buildings that are individually listed on the National Register include Warren Opera House Block and Hetherington Block (1896), Adair County Democrat-Adair County Free Press Building (1903), and the Hotel Greenfield (1920).
Lucas County Courthouse Square Historic District is a nationally recognized historic district located in Chariton, Iowa, United States. It was listed on the National Register of Historic Places in 2014. At the time of its nomination the district consisted of 76 resources, including 56 contributing buildings, one contributing site, one contributing structure, three contributing objects, 14 noncontributing buildings, one noncontributing structure, and one noncontributing object. The historic district covers the city's central business district in the original town plat. The buildings were either built or remodeled between 1867 and 1963, and range from one to three stories in height. They all have brick exteriors. Of the older buildings, the commercial Italianate style is dominant.
The Poplar Rural District is a nationally recognized historic district located north of Jacksonville, Iowa, United States. It was listed on the National Register of Historic Places in 1992. At the time of its nomination the district consisted of 55 resources, including 29 contributing buildings, one contributing site, five contributing structures, one contributing object, 15 non-contributing buildings, and four non-contributing structures. The 36 contributing resources include three houses, 12 barns, 14 outbuildings, which are all included as buildings. The three corn cribs and the two granaries/corn cribs are the structures. A concrete post fence line is the object, and the landscape of the district is the site. They are all associated with the largest rural settlement of Danish immigrants in the United States. The farmsteads are located on the hilltops or along the hillsides. The latter appear to be somewhat linked to the ethnic heritage of the Danish immigrants who tended to locate their farmsteads on sheltered hillsides. The period of significance starts with the construction of the original Jackson #1 schoolhouse in 1884, and concludes with the construction of the second Jackson #1 schoolhouse in 1923.
The McGregor Commercial Historic District is a nationally recognized historic district located in McGregor, Iowa, United States. It was listed on the National Register of Historic Places in 2002. At the time of its nomination the district consisted of 60 resources, including 51 contributing buildings, one contributing site, one contributing structure, and seven noncontributing buildings. Unlike most river towns in Iowa the central business district does not follow along the Mississippi River, but moves away from it. It is linear in shape, following Main Street, which runs from the southwest to the northeast in a narrow valley between two 400-foot (120 m) bluffs. The narrow valley ends at the river.
Fort Dodge Downtown Historic District is a nationally recognized historic district located in Fort Dodge, Iowa, United States. It was listed on the National Register of Historic Places in 2010. Additional documentation for the district was approved by the National Park Service on January 4, 2019. At the time of its nomination it contained 177 resources, which included 100 contributing buildings, one contributing site, one contributing structure, five contributing objects, 64 non-contributing buildings, three non-contributing structures, and three non-contributing objects. The district covers the city's central business district, mainly along Central Avenue, but also along the adjoining streets as well. Commercial development in the district began with the city's original plat in 1854 and continued through the opening of the Crossroads Mall in 1964. Webster County Courthouse (1902), First National Bank Building (1908), and the Wahkonsa Hotel (1910) are all located in the district and are individually listed on the National Register.
The Eldora Downtown Historic District is a nationally recognized historic district located in Eldora, Iowa, United States. It was listed on the National Register of Historic Places in 2009. At the time of its nomination the district consisted of 84 resources, including 65 contributing buildings, one contributing site, three contributing objects and 15 non-contributing buildings. The district takes in the city's central business district, which also includes its governmental, educational, and religious activities. It is located in the original town plat from 1853. Development began around the public square and spread out from there. The present building stock is second generation at the earliest. The oldest extant buildings were built in the 1870s, although the greatest number of buildings were constructed in the 1890s. There were also peak years of construction in the 1910s, and the late 1930s and 1940s. The commercial buildings generally range from one to two stories, but the tallest structure is three stories in height. They are primarily composed of brick construction. Late Victorian and various revival styles from the late 19th and 20th centuries are dominant. The non-commercial buildings include four government buildings, four churches, three residences, a hospital, and a school.
The Mason City Downtown Historic District is a nationally recognized historic district located in Mason City, Iowa, United States. It was listed on the National Register of Historic Places in 2005. At the time of its nomination it contained 93 resources, which included 63 contributing buildings, one contributing site, four objects, 22 non-contributing buildings, and three non-contributing objects. Platted in 1855, Mason City is a commercial and industrial center for north central Iowa. It was also a railroad center, but the tracks bypassed the central business district in order to serve the industries located on the north side of town and the wholesale enterprises on the south side. Central Park, a public square, was part of the city's original plat and is the contributing site.
The Hawkinsville Commercial and Industrial Historic District is a historic district in Georgia, United States that was listed on the National Register of Historic Places in 2004.
Old Town Historic District is a nationally recognized historic district located in Ames, Iowa, United States. It was listed on the National Register of Historic Places in 2004. At the time of its nomination it consisted of 249 resources, which included 191 contributing buildings, one contributing site, and 57 non-contributing buildings. The district is a residential area located north of the central business district. Between the two is a "civic corridor" made up of government buildings, churches and fraternal organizations. The earlier residences here were built of brick, but from about 1890 to 1910 they are all of wood construction. Brick reappears in 1910, but as a secondary building material. The houses are from one to two stories in height. They reflect the Late Victorian styles as well as the Colonial Revival styles of the early 20th century. The houses generally have a detached garage behind the house, facing an alley. The Prof. J.L. Budd, Sarah M., and Etta Budd House (1885) is individually listed on the National Register.
The Marion Commercial Historic District is a nationally recognized historic district located in Marion, Iowa, United States. It was listed on the National Register of Historic Places in 2009. At the time of its nomination it consisted of 41 resources, which included 29 contributing buildings, one contributing site, one contributing structure, two contributing objects, and eight non-contributing buildings. The historic district covers the city's central business district. The development of this area largely occurred when Marion was the county seat of Linn County (1838-1919). There are no county government buildings extant from this era. The city was also a division point for the Chicago, Milwaukee, St. Paul and Pacific Railroad in the late nineteenth and early twentieth centuries.
The Red Oak Downtown Historic District is a nationally recognized historic district located in Red Oak, Iowa, United States. It was listed on the National Register of Historic Places in 2016. At the time of its nomination it contained 104 resources, which included 73 contributing buildings, eight contributing objects, one contributing site, 15 non-contributing buildings, six non-contributing objects, and one non-contributing structure. The historic district covers most of the city's central business district. It is a flat area of land in an otherwise hilly region. The district is centered on Fountain Square, a public green space around which the town had been platted in 1857. A second public square was added in 1890 for the Montgomery County Courthouse after Red Oak won a special election to move the county seat from Frankfort.
The Camp Harlan-Camp McKean Historic District, also known as the Hugh B. and Mary H. Swan Farmstead and the Springdale Stock Farm, is a nationally recognized historic district located northwest of Mount Pleasant, Iowa, United States. It was listed on the National Register of Historic Places in 2013. At the time of its nomination it consisted of eight resources, which includes two contributing buildings, one contributing site, one contributing object and four non-contributing buildings.
The Colfax Spring City Commercial Historic District is a nationally recognized historic district located in Colfax, Iowa, United States. It was listed on the National Register of Historic Places in 2018. At the time of its nomination it contained 48 resources, which included 28 contributing buildings, two contributing sites, two contributing structures, 12 non-contributing buildings, and four non-contributing structures. Colfax was platted in 1866 or 1867 as a railroad and farm-to-market town along the Chicago, Rock Island and Pacific Railroad. Coal mines were also located to the south of town. Mineral water was discovered in the area in 1875, which led to the development of the mineral water-based health industry in Colfax. The historic district represents the growth during this time period. After the health-related mineral water industry declined, Colfax expanded its farm-to-market economy in the late inter-war and post-World War II years.
