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Mackworth Island Causeway

Street Views 


The Mackworth Island Causeway is an unusual crossing of the Casco Bay that connects mainland Portland to Mackworth Island.

The majority of the bridge is a composite beam bridge causeway, however a small 102-foot plate girder swing bridge is also present. The swing span no longer operates for boats, the center pier has been removed, and two new piers have been inserted on either side, essentially converting the swing span to a fixed plate girder span.

The causeway is privately owned by the Mackworth Island Recreational Society, which is not related to the Portland Recreation Department. Originally, a toll of $0.50 was required to cross the causeway, however tolls were discontinued in 2009.

The causeway currently is posted under several restrictions. There is a weight limit of 4 tons, and only one vehicule may traverse the causeway at any given time. Additionally, all vehicles entering or leaving the causeway are subject to search.

MaineDOT has attempted to purchase the causeway on numerous occasions, but their offers have been refused due to their poor record of historic bridge preservation. It appears that the Recreational Society is committed to preserving the causeway, even with the swing span severely altered.


Causeway with through plate girder (former swing) bridge over Casco Bay on Andrews Avenue
Portland, Cumberland County, Maine
Restricted - weight limit 4 tons, one vehicle at a time, all vehicles subject to inspection
Built 1955; rehabilitated 2015
Causeway with through plate girder (former swing) bridge
Length of largest span: 102.0 ft.
Total length: 2,112.0 ft. (0.4 mi.)
Eligible for the National Register of Historic Places
Also called
Andrews Avenue Causeway
Approximate latitude, longitude
+43.69233, -70.23702   (decimal degrees)
43°41'32" N, 70°14'13" W   (degrees°minutes'seconds")
Approximate UTM coordinates
19/400311/4838444 (zone/easting/northing)
Average daily traffic (as of 2016)
Inventory number
BH 80937 (Bridgehunter.com ID)
Inspection report (as of November 2018)
Overall condition: Fair
Superstructure condition rating: Satisfactory (6 out of 9)
Substructure condition rating: Very Good (8 out of 9)
Deck condition rating: Very Good (8 out of 9)
Sufficiency rating: 21.9 (out of 100)
View more at BridgeReports.com

Update Log 

  • March 31, 2018: New Street View added by Dana and Kay Klein
  • March 31, 2018: Added by Amanda