Milton–Madison Bridge as seen from Milton, Kentucky
|Carries||2 lanes of US 421|
|Locale||Milton, Kentucky and Madison, Indiana|
|Other name(s)||Madison–Milton Bridge|
|Total length||3,184 feet (970 m)|
|Width||20 feet (6.1 m)|
|Longest span||220 m|
The Milton–Madison Bridge (also known as the Harrison Street Bridge) is a continuous truss bridge that connects Milton, Kentucky and Madison, Indiana. It carries approximately 10,000 cars a day. The old structure was replaced with a completely new continuous truss which was constructed on temporary piers adjacent to the operational span between 2011 and 2012 and slid into place after demolition of the old span using a construction method called "truss sliding." 
This two lane vehicular bridge is the Ohio River crossing for U.S. Route 421. It has a main span of 600 feet (180 m) and total length of 3,184.2 feet (970.5 m). It has a deck width of a mere 20 feet (6.1 m), and above the deck the vertical clearance is 16.8 feet (5.1 m). This bridge is the only vehicular crossing of the Ohio River for 26 miles (42 km) going upstream (the Markland Bridge near Vevay, Indiana) and 46 miles (74 km) downstream (the John F. Kennedy Memorial Bridge in Louisville).
Built by J.G. White Engineering Corp., construction was started in 1928, and completed in 1929, at the cost of $1,365,101.84. It was opened for traffic on December 20, 1929. Originally a toll bridge, on November 1, 1947 at noon the toll was removed.
The bridge is in the process of replacement, as the original bridge was "functionally obsolete" and "structurally deficient." It has a sufficiency rating of 33 out of a possible 100; its superstructure condition rating is considered "poor". Modern trucks are unable to use the bridge safely. One of the boons to the new bridge would be to aid a $20 million "resort and entertainment center" where previously a cotton mill stood.
A Milton–Madison bridge study was begun by the Indiana Department of Transportation and Kentucky Transportation Cabinet on August 26, 2008. The study must take in account the Madison Historic District, which is a National Historic Landmark, and the National Environmental Policy Act.
The Indiana Department of Transportation (INDOT) in a partnership with the Kentucky Transportation Cabinet (KYTC) has designed a new bridge to replace the current bridge. The new project is headed mostly by INDOT. The bridge will be removed except for several piers in the waterway, which will be rehabilitated and widened to accommodate a new, wider steel-truss superstructure. Scour mitigation will also be performed on the existing piers. The new bridge will also feature an ADA-compliant pedestrian walkway. Construction for the new bridge began in the fall of 2010, with the old bridge remaining open during work on the piers. Walsh Construction Company planned to close the bridge for only 10 days during construction rather than an anticipated year-long closure. The team will use an innovative construction method called "truss sliding" to "slide" the 3,181-foot-long (970 m) truss into place along steel rails and plates.
The cost of the replacement was $103.7 million.
On March 11, 2014, only four days before the truss slide was scheduled to begin, construction workers were installing a mechanism to facilitate the slide when a steel bearing on the southeast corner of the bridge dislodged, causing the bridge to drop by at least 1 foot (30 cm) and injuring one worker. Work was conducted to replace the steel bearing ten days later and the bridge opened to traffic at 7:20 PM on April 17, 2014.
- "Kentucky officials announce kickoff of bridge study". Kentuckiana Publishing, Inc. September 2008. Retrieved 2009-01-30.
- "Milton–Madison bridge project milestones". Retrieved 2014-04-21.
- Baughn, James (2002–2009). "Madison-Milton Bridge". Historic Bridges of the United States. Retrieved 2009-01-30.
- "The Story of the Splendid Milton–Madison Bridge". nkyviews.com. Retrieved 2009-01-30.
- Weidenbener, Lesley (January 30, 2009). "Indiana panel may focus on Ohio River bridges". Courier-Journal. Retrieved 2009-01-30.[dead link]
- "Indiana, Kentucky highway officials launch effort to build new Milton–Madison bridge". FOX 41 (Louisville). Retrieved 2009-01-30.
- "Milton–Madison Bridge Official Construction site". Retrieved 2011-02-05.
- "Raising Expectations", Bridge Design & Engineering, 28 August 2012, retrieved 8 August 2014
- Godfrey, Courtney (March 11, 2014). "No word on when Milton–Madison Bridge will reopen after accident". Louisville, Kentucky: WDRB. Retrieved March 12, 2014.
- Official website of the construction project
- Milton–Madison Bridge at Bridges & Tunnels
- Madison–Milton Bridge at Historic Bridges of the United States