A. Murray MacKay Bridge
The A. Murray MacKay Bridge locally known as "the new bridge" is the second suspension bridge linking the Halifax Peninsula with Dartmouth, Nova Scotia, and opened on July 10, 1970. The A. Murray MacKay Bridge measures 1,200 m (3,900 ft) with the total of all suspended spans being 739.9 m (2,427 ft) in length, carrying four traffic lanes with posted speed limits of 70 kilometres per hour (43 mph). Pedestrians and bicycles are not permitted on the A. Murray MacKay Bridge; they may use dedicated lanes on the Angus L. Macdonald Bridge instead. As of 2008, the bridge charges a toll (75¢,or MACPASS electronic toll system, 60¢ tokens were once used but are no longer accepted) to cross for regular passenger vehicles. Larger vehicles have higher tolls proportional to the number of axles. The Halifax-Dartmouth Bridge Commission is exploring the idea of moving entirely to electronic tolls to avoid handling tokens or cash. The A. Murray MacKay Bridge is the only harbour bridge which permits semi-trailers and large trucks. The bridge is named after Alexander Murray MacKay, chairman of the Halifax-Dartmouth Bridge Commission from 1951 to 1971 and past chief executive officer of MT&T. MacKay was instrumental in having both the Angus L. Macdonald Bridge and his namesake structure built during his tenure at the commission.

Africville controversy
A major political controversy preceded construction of the MacKay Bridge when the city of Halifax expropriated residents from the community of Africville near the Halifax abutment. New highway interchanges were built with the northern end of Barrington Street ( Trunk 3), and an extension of Robie Street and the Bedford Highway ( Trunk 2), as well as realignments of Highway 102 and Bayers Road. Some CN railway trackage in the area also had to be realigned.

Impact on development
The building of the MacKay Bridge, along with Highway 111, initiated a development boom in Dartmouth which eclipsed that created by the Macdonald Bridge during the 1950s and 1960s. The Burnside Business Park, the Mic Mac Mall shopping centre, and several residential developments in the Albro Lake neighbourhood in Dartmouth's north end during the 1970s can be directly attributed to the bridge's construction.

In 1970, a decision was made to finance the construction of the bridge with low-interest loans denominated in foreign currencies. That decision saved money in the short term and allowed the tolls to be kept low. However, the subsequent decline in the value of the Canadian dollar against the German Mark and the Swiss franc wiped out the interest cost advantage, then added massively to annual debt servicing costs. As a result, at its peak, the Commission's debt amounted to nearly $125,000,000, nearly triple the total cost of construction for both harbour bridges of about $42,000,000.

Renaming controversy
Following the death of former Nova Scotia premier Robert L. Stanfield in 2003, there was a motion made to rename the MacKay Bridge to honour Stanfield (in 2007 the Halifax International Airport was renamed to Halifax Stanfield International Airport, and several new schools and institutions being built are being considered for the Stanfield name), however the Stanfield family did not want any current structures already named for persons to be changed for Stanfield's sake.