1905-1924 Map Showing Bridges over the Chicago River and Part of Its Branches
DESCRIPTION
By: Thomas G. Pihlfeldt
Date: 1905 / 1924 (dated) Chicago
Dimensions: 36 x 23 inches (91.5 x 58.5 cm)
This large-format technical map was prepared by the City of Chicago Bureau of Engineering as a working document to evaluate, record, and modernize the city’s extensive bridge infrastructure. This map is quite rare with only one other know example in institutional holding.
First compiled in March 1905, the map was updated multiple times, with the most recent revision dated December 16, 1924. The example at hand appears to be a photo-static copy, likely used as a reference copy within the city’s engineering department, but it bears a genuine ink signature by Thomas G. Pihlfeldt, the city’s Engineer of Bridges. This detail confirms its use as an active working document within the office responsible for Chicago’s early 20th-century bridge modernization efforts.
Map Scope and Layout
The map provides a detailed survey of all known bridges over the Chicago River, including its Main Stem, North Branch, and South Branch, as well as portions of the Calumet and Little Calumet Rivers. It spans the urban corridor from Evanston Avenue (now Broadway) in the north to the southern industrial reaches of the Calumet River. Two inset maps extend the coverage, showing the broader Lake Calumet region and crossings along the Little Calumet River, underscoring the significance of waterway infrastructure to both freight and passenger movement in Chicago’s vast and growing industrial zones.
Bridge Types, Condition, and Planned Improvements
This map was created at a pivotal moment when Chicago was transitioning away from 19th-century wooden and iron drawbridges toward the more efficient and mechanically robust bascule bridge. Many of the replacements proposed on this map were ultimately constructed during the 1920s and 1930s and remain in place today as part of the city’s iconic river-crossing network. The document functions not only as a record of what existed but also as a visual blueprint of what was envisioned, its layered notes, multiple revision dates, and precise classifications point to its use in real-time urban planning and structural assessment.
Running along the left margin is a comprehensive bridge inventory, listing each crossing by street name, year of construction, and bridge type. This list, accompanied by a symbol key at center-left, also notes whether a structure was slated for replacement or modernization. The classification system identifies several varieties of movable and fixed spans, including old combination drawbridges, rolling and trunnion bascule bridges, vertical lift bridges (such as Strauss designs), and temporary trestles or fixed truss spans. Each bridge’s condition is implied through notations, with many older structures designated for eventual replacement—signaling the city’s growing concern with congestion, reliability, and mechanical obsolescence.
A Signature of Authority
The presence of Thomas G. Pihlfeldt’s original signature lends further significance to this piece. As the Engineer of Bridges for the City of Chicago, Pihlfeldt played a central role in the design and construction of the city’s major river crossings during this era, including his involvement with the landmark Michigan Avenue Bridge. His signature on this map confirms it was not merely an internal reference but a formally approved document used in ongoing planning and evaluation. As such, the map stands as a rare and authoritative artifact from Chicago’s golden age of infrastructure development; a period when engineering expertise, municipal ambition, and a dynamic urban landscape converged to reshape the way the city moved across its rivers.
Condition: Map is in excellent condition, issued folded now somewhat flat with not visible damage save for some soiling on the verso. Bold blue color is quite attractive over light tan paper.
Inventory #13103
CONDITION
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