The I Street Bridge is a swing span which crosses the Sacramento River and is owned by the Union Pacific Railroad. The top deck of this 400-foot-long structure carries automotive traffic from I Street in Sacramento to C Street in West Sacramento. The bottom deck carries the tracks of the Union Pacific Railroad.
The I Street Bridge was completed in 1912 as a cooperative between the Southern Pacific Railroad, Yolo County and Sacramento County. The span would become part of the State Highway System when Legislative Route Number 50 was extended to Sacramento in 1933.
California State Route 16 would be assigned to the I Street Bridge when the initial run of Sign State Routes was announced in August 1934. The structure became part of California State Route 24 when said highway was extended to Oakland in 1935. California State Route 24 would continue to use the I Street Bridge until it was realigned onto the Jibboom Street Bridge (Legislative Route Number 232) in 1960.
The I Street Bridge was removed as part of the State Highway System and as part of California State Route 16 in 1984. The final design of the replacement highway span was selected during 2020 but has been delayed due to budget shortfalls between the cities of Sacramento and West Sacramento.
The I Street Bridge can be seen carrying California State Routes 16 and 24 below on the 1938 Division of Highways map.
Part 1; the history of the I Street Bridge
The predecessor to the I Street Bridge at the Sacramento River was constructed by the California Pacific Railroad Company. The structure was located just north of modern I Street and became functional on January 29, 1870, when the first train crossed.
The California Pacific Railroad Company can be seen in a public domain photo in 1870 shortly after opening. Unlike the later I Street Bridge this structure only served trains. The swing turntable of the structure can be seen in the center of the photo.
The 1870-era California Pacific Railroad Bridge can be seen crossing the Sacramento River between Sacramento and Washington (now West Sacramento) on the 1907 United States Geological Survey map of Davisville.
The Southern Pacific Railroad, Yolo County and Sacramento County came to an agreement on construction of the I Street Bridge on February 14, 1910. The project initially faced difficulties due to the hesitancy of Yolo County due to the lack of support by the Northern Electric Railroad. The Southern Pacific eventually threatened not to construct an automotive road deck atop the structure which saw Yolo County relent. Yolo County would officially endorse construction of a road deck atop the I Street Bridge on September 8, 1910.
Construction of the I Street had commenced on June 8, 1910. The structure would be completed on April 29, 1912, at a cost of approximately $1,000,000. Like the 1870-era railroad span the I Street Bridge retained a turntable swing design.
In 1933 the I Street Bridge would be added to the State Highway System when Legislative Route Number 50 was extended into Sacramento. The structure would become a component of California State Route 16 when the initial run of Sign State Routes was announced in the August 1934 California Highways & Public Works.
California State Route 24 would be extended from Woodland to Oakland in 1935 following the Division of Highways acquiring the Kennedy Tunnel. The highway was multiplexed over the I Street Bridge into Sacramento along with California State Route 16.
The October 1935 California Highways & Public Works announced the Jibboom Street Overhead as a recommended project. The then proposed span would serve as a connection between Jibboom Street and the I Street Bridge. Concepts of the Jibboom Street Overhead were shared in the July 1936 California Highways & Public Works. The project is noted to be a Federal cooperative and included a replacement for the original eastern approach to the I Street Bridge. The original eastern approach landed at I Street just west of 2nd Street. The new approach was planned to be elongated towards 3rd Street. Jibboom Street is shown to have originally to connected to 2nd Street via an at-grade crossing of the Southern Pacific Railroad.
The Jibboom Street Overhead and realigned eastern approach to the I Street Bridge were featured in the October 1937 California Highways & Public Works. The improved structures were dedicated by the Governor on October 1, 1937.
The I Street Bridge can be seen carrying California State Routes 16 and 24 below on the 1938 Division of Highways map.
1949 Legislative Chapter 1467 defined a duplicate Legislative Route Number 207 as a new State Highway between Sacramento and Marysville. This highway incorporated the Jibboom Street Overhead branching north of the I Street Bridge. The corridor was originally subject to the provisions of the Collier Burns Act of 1947 regarding maintenance. The duplicate Legislative Route Number 207 would be reassigned as Legislative Route Number 232 by way of 1951 Legislative Chapter 1562. The Collier Burns Act provision the highway was subject to was removed in 1955.
Legislative Route Number 232 first appears as an active State Highway on the 1958 Division of Highways map. The highway is shown to terminate at the I Street Bridge via the Jibboom Street Overhead.
Legislative Route Number 232 first appears as the then new alignment of California State Route 24 on the 1960 Division of Highways map. This realignment left only California State Route 16 crossing the Sacramento River via the I Street Bridge.
Following the 1964 State Highway Renumbering the routing of California State Route 24 was truncated to the San Francisco Bay Area. California State Routes 99 was defined as running through Sacramento and California State Route 70 was originally signed to terminus at Capitol Mall. California State Routes 99 and 70 would initially use the eastern I Street Bridge approach to reach the Jibboom Street Overhead. These new highways can be seen in downtown Sacramento on the 1965 Division of Highways map.
The original alignments of California State Routes 99 and 70 on the Jibboom Street Overhead were intended to be temporary. Following the completion of Interstate 5 north of downtown Sacramento during the late 1960s both State Routes would multiplex the freeway. This multiplex can be seen on the 1970 Division of Highways map.
The I Street Bridge was added to the National Register of Historical Places on April 22, 1982. The surface alignment of California State Route 16 between Woodland-Sacramento (specifically Conaway-Sacamento) and the I Street Bridge were relinquished to local authorities in 1984. Regardless California State Route 16 is shown multiplexing Interstate 5 between Woodland-Sacramento on the 1986 Caltrans State Map.
Even the 1990 Caltrans State Highway Map shows California 16 multiplexed with Interstate 5 between Woodland-Sacramento. It is unclear what if any field signage existed to indicate a connecting route between the western and eastern segments of California State Route16. Presently there are no reassurance signs linking both the western and eastern segments of the highway.
In 2011 the cities of Sacramento and West Sacramento completed the Sacramento River Crossing Alternatives Study. Said study concluded that the I Street Bridge was in need of replacement due to having become obsolete for highway traffic (this study did not pertain to rail traffic). The final replacement span concept drawings were released to the public on February 21, 2020.
The new Sacramento River Crossings span is slated to be located directly north of the I Street Bridge and West Sacramento into the Sacramento's Railyards District. The structure is planned as a vertical lift span with a total length of 860 feet. The structure was originally slated to break ground during 2024 but has been delayed due to budget shortfalls. The span is estimated to cost approximately $200,000,000.
Edit 10/27/2025: Since this blog was written in May 2025 there has been minor news from the California Transportation Commission (CTC) regarding replacement of the I Street Bridge. The CTC on October 4, 2025, approved the replacement span project for future consideration of funding.
Part 2; exploring the I Street Bridge
The final surface alignment of California State Route 16 in downtown Sacramento had westbound traffic following 5th Street from Capitol Mall to reach I Street. There are numerous button copy gantries can be found at this intersection which are evidence of the former State Highway corridor.
California State Route 16 westbound would have followed signage directing traffic over the I Street Bridge into West Sacramento. The roadway deck is narrow as it and carries an overhead clearance of 14 Feet 8 Inches. Upon entering West Sacramento traffic merges onto to C Street.
This view is facing east along the grade of the now Union Pacific Railroad to the bottom deck of the I Street Bridge.
These photos of the I Street Bridge are from Sacramento River Trail in Old Sacramento.
These photos are facing southbound on the Jibboom Street Overhead heading towards I Street. California State Routes 24, 99 and 70 all would have turned left upon towards downtown Sacramento reaching I Street.
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