SH 120 Bridge is a historic concrete slab and girder bridge in Fremont County, Colorado. Built in 1925, the bridge carries State Highway 120 over a draw and represents an early use of reinforced concrete bridge construction by the Colorado Highway Department. Though modest in size, the bridge is an important surviving example of the standardized concrete structures that helped modernize Colorado’s highway system in the 1920s.
The 1920s were a major period of change for Colorado roads and bridges. As automobile travel increased, the state needed more durable roads, safer crossings, and bridges capable of supporting heavier vehicles. The Colorado Highway Department responded by developing and refining standard bridge plans, including designs for concrete slab bridges, concrete girder bridges, and steel I-beam structures. These standardized designs helped the department build bridges more efficiently while improving consistency across the state highway network.
SH 120 Bridge reflects this early period of professionalized highway bridge design. Concrete slab and girder bridges use reinforced concrete components to distribute traffic loads across the bridge span and into the supporting substructure. Compared with earlier timber structures, concrete bridges offered greater durability and lower long-term maintenance needs. Their simple forms also made them practical for smaller crossings where a large truss, arch, or steel girder bridge was unnecessary.
Although the bridge is officially identified simply as “Bridge” in CDOT records, its location on State Highway 120 gives it a clear public identity within the Historic Bridges of Colorado effort. The bridge’s setting and function tie it to early highway improvements in Fremont County and to the broader statewide shift from older road systems toward paved, engineered highways designed for automobile travel.
SH 120 Bridge has been determined eligible for the National Register of Historic Places under Criterion A in the area of Transportation and Criterion C in the area of Engineering. Its transportation significance comes from its association with early highway improvement and paving. Its engineering significance comes from its early use of concrete construction by the Colorado Highway Department and its survival as a rare, intact example of an early highway bridge.
The bridge’s character-defining features include its reinforced-concrete deck girder superstructure and its original concrete post-and-beam railings. These elements help convey the bridge’s historic engineering design and distinguish it from later highway structures. The original railings are especially important to the bridge’s visual identity, reflecting the design vocabulary used by the Colorado Highway Department during the period when concrete was becoming a standard material for state highway bridges.
SH 120 Bridge is also important because it represents a small-scale but meaningful part of Colorado’s transportation landscape. Historic bridge preservation often focuses on large or visually dramatic crossings, but smaller bridges like this one were essential to the everyday operation of the state highway system. They carried local traffic, supported industrial and agricultural movement, and helped make rural and regional travel more reliable.
As part of the Historic Bridges of Colorado preservation effort, SH 120 Bridge has been identified as a preservation-priority bridge. CDOT selected the bridge for Group B, recommending development of an individual bridge management plan because it is a rare example of an early highway bridge. This designation recognizes that even modest structures can possess significant historical and engineering value when they retain integrity and represent important phases in bridge construction.
Preservation of SH 120 Bridge presents the familiar challenge of maintaining an active transportation structure while protecting its historic character. Concrete bridges from the 1920s may face issues related to rail condition, concrete deterioration, drainage, or changing roadway safety standards. A preservation-focused management plan can help identify appropriate maintenance and rehabilitation strategies while retaining the features that make the bridge historically significant.
SH 120 Bridge helps tell a quieter but important part of Colorado’s bridge history. It reflects the transition from early road building to a more systematic state highway program and demonstrates how standardized reinforced concrete designs shaped everyday transportation infrastructure. Its preservation ensures that this practical, early phase of highway engineering remains represented within the state’s historic bridge network.
This bridge is one of the 23 preservation-priority bridges featured in Colorado Preservation, Inc.’s Historic Bridges of Colorado listing. View the full Historic Bridges of Colorado overview to learn more about the statewide preservation effort.