The Governor Thomas Johnson Memorial Bridge (also referred to as the Thomas Johnson Bridge and the Solomons Bridge) is a 1.37-mile (2.20 km) bridge in Maryland over the lower Patuxent River joining Calvert and St. Mary's counties. The bridge, named for the first governor of Maryland, Thomas Johnson, saw construction start in 1972 and opened to traffic on December 17, 1977.

The bridge, carrying an average of 33,000 vehicles a day on Maryland Route 4 (MD 4), is one of two crossings of the Patuxent River in Southern Maryland (the other is the Benedict Bridge approximately 20 miles up river, where MD 231 connects Calvert County and Charles County).

The north end of the bridge, on the Calvert side, is located in Solomons. Just prior to the bridge, MD 2-4 narrows from four lanes to two, and MD 2 exits the highway, passing under the bridge and heading toward downtown Solomons. MD 4 continues onto the bridge itself and over the Patuxent River.

The bridge, carrying two lanes and no shoulders, rises to a height of approximately 160 feet (49 m) tall. From the top of the bridge, one can see the entire town of Solomons, the runways at the Patuxent River Naval Air Station, the Dominion Cove Point LNG, and the Chesapeake Bay.

The bridge begins in St. Mary's County, before even reaching the Patuxent River. It passes over Town Creek first, then crosses over the unincorporated community of Spencers Wharf on a viaduct. Once over the community, the bridge passes over the Patuxent River, entering Calvert County. Shortly after reaching land, MD 2 joins MD 4 and cross Calvert County together for a long concurrency on a four-lane divided highway.

The Thomas Johnson Bridge is a variable depth beam bridge. Massive concrete pilings hold the bridge up over the river.

In the summer of 1988, cracks were found in the foundation of the Thomas Johnson Bridge, causing it to be closed for repairs over several months. People traveling north into Calvert County were forced to make a half-hour detour to the Benedict Bridge. People traveling south into St. Mary's County were likewise forced to either utilize the Benedict Bridge or take a free charter boat across the Patuxent River to a park and ride lot on the southern side.

As of September 2007^[update], there has been much talk and public debate over either expanding the Thomas Johnson Bridge by adding a parallel span, or replacing the bridge with a four-lane span. The reasons for such proposals are twofold. First, the recent increase in the amount of traffic of commuters traveling to and from the Patuxent River Naval Air Station has made the two-lane, single-span bridge functionally obsolete. Traffic on the bridge during rush hour can cause back-ups all the way back to the Route 235 intersection, and instances where there is an accident on the bridge itself can cause total gridlock.^{[citation needed]}