Question: What is the name of the only "Des Moines" cruiser that still exists?

Context paragraphs:
Des Moines Building: The Des Moines Building is an historic building located in downtown Des Moines, Iowa, United States.  It was built in 1930 based on the designs of the Des Moines architectural firm of Proudfoot, Rawson, Souers & Thomas.  It is a combination of the Art deco and Art Moderne styles.  The 14-story structure rises to a height of 190 ft .  The former office building was abandoned and in May 2011 the city of Des Moines declared it a public nuisance so as to acquire it to be redeveloped.  In November of the same year they sold the building for $150,000 to Des Moines Apartments, LP who developed it into 146 loft apartments.  It was listed on the National Register of Historic Places in 2013.

United States Naval Shipbuilding Museum: The United States Naval Shipbuilding Museum is a private non-profit museum in Quincy, Massachusetts featuring USS "Salem" (CA-139), a heavy cruiser docked at the former Fore River Shipyard where she was laid down in 1945.  The museum was established in 1993, in response to efforts by local officials and volunteers to revive the shipyard area after operations at Fore River ended in 1986.  Several exhibits on board "Salem" relating to United States naval history and shipbuilding are featured along with dockside fixtures and a miniature golf course.

Des Moines River Locks No. 5 and No. 7: Des Moines River Locks No. 5 and No. 7, also known as the Bonaparte and Keosauqua Locks, comprise a discontinuous historic site located along the Des Moines River in Van Buren County, Iowa, United States.  Lock No. 5 is located in a riverfront park in Bonaparte, and lock No. 7 is located near Keosauqua.  The locks are the only structures that are known to exist for the Des Moines River Improvement Project.  Steamboats were the primary means of transportation into the interior of Iowa, but the river was only navigable at certain times of the year and that made the shipping season too short and unpredictable.  In 1846 the Iowa Legislature conceived a plan to build a lock and dam system along the Des Moines River to make it navigable from the Mississippi River to the city of Des Moines.  These two locks and a third at Bentonsport, non extant, were the only locks of the 28 planned locks and dams that were completed.  The project ended in 1858 because it was mismanaged, and the Keokuk and Des Moines River Railroad was being developed to cover the same territory at the same time.  Two dams had also been completed, but they have since been removed.  Even though the project was never completed, navigation was

Des Moines Symphony: The Des Moines Symphony (DMSO) is a United States symphony orchestra based in Des Moines, Iowa.  The current conductor is Joseph Giunta.  Established in 1937 as the Des Moines Civic Orchestra, the orchestra performs both Masterworks and Pops concerts as well as Iowa's largest single-day concert event, Yankee Doodle Pops.  The orchestra principally performs at the Civic Center of Greater Des Moines located in downtown Des Moines.

Perry and Brainard Block: The Perry and Brainard Block is an historic building located in Des Moines, Iowa, United States.  The structure was built between 1888 and 1889 and served as the city hall for the suburb of North Des Moines.  When it was constructed it was the largest commercial building in North Des Moines.  It is significant in the Annexation Movement in Des Moines and its suburbs in the late 19th century.  It is the only known public building that has survived from this period.  It was listed on the National Register of Historic Places in 1996 as a part of the "Towards a Greater Des Moines MPS".  It was listed in 2011 as one of Iowa's Most Endangered Properties.

Des Moines, Iowa: Des Moines is the capital and the most populous city in the U.S. state of Iowa.  It is also the county seat of Polk County.  A small part of the city extends into Warren County.  It was incorporated on September 22, 1851, as Fort Des Moines, which was shortened to "Des Moines" in 1857.  It is on and named after the Des Moines River, which likely was adapted from the French colonial name, "Rivière des Moines," meaning "River of the Monks." The city's population was 203,433 as of the 2010 census.  The five-county metropolitan area is ranked 91st in terms of population in the United States with 599,789 residents according to the 2013 estimate by the United States Census Bureau.

Downtown Des Moines: Downtown Des Moines is the central business district of Des Moines, Iowa and the Greater Des Moines Metropolitan Area.  Downtown Des Moines is defined by the City of Des Moines as located between the Des Moines River to the east, the Raccoon River to the south, Center Street to the north, and 18th and 15th Streets to the west.

Saylorville Lake: Saylorville Lake is a reservoir on the Des Moines River in Iowa, United States.  It is located 11 mi upstream from the city of Des Moines, and 214 mi from the mouth of the Des Moines River at the Mississippi River.  It was constructed as part of a flood control system for the Des Moines River as well as to aid in controlling flood crests on the Mississippi, of which the Des Moines is a tributary.

USS Salem (CA-139): The third USS "Salem" (CA-139) is one of three "Des Moines"-class heavy cruisers completed for the United States Navy shortly after World War II.  Commissioned in 1949, she was the world's last heavy cruiser to enter service and the only one still in existence.  She was decommissioned in 1959, after serving in the Atlantic and Mediterranean.  She is open to the public as a museum ship in Quincy, Massachusetts.

James Sansom Carpenter House: The James Sansom Carpenter House was significant to Des Moines cultural history from 1906 to 1939.  The 13 acre property named Oakwood estate by its owners J. S. Carpenter and his Spouse Florence L. Carpenter because of the old growth oak forestation.  The Carpenters' collection was deemed by art critics as one of the finest collections of etchings and lithographs in America.  The house held the Carpenter collection of 125 paintings and 350 etchings.  J. S. Carpenter was also known as Sannie or Sandy after his oddly spelled middle name.  J. S. Carpenter, a bridge building magnet, founded the Des Moines Association of Fine Arts in 1916.  The Association members each contributed $100.00 annually for the purchase of paintings and sculptures.  The members also received a 25% discount on art purchased at Association events.  Carpenter was known as the Guru of fine arts by the Des Moines community.  Visiting artists and dignitaries came to Des Moines to sell their art and often stayed with the Carpenter's at Oakwood.  Carpenter was president of the Association from its inception until his death of heart disease in 1939.  The Association transformed into the Edmundson Art Museum in 1940 under the auspices of Association Executive member, and Carpenter's close friend Jay N. (Ding) Darling.  Darling as President of the Edmundson Art Foundation merged the original collection into the present day Des Moines Art Center.

Supporting paragraphs: United States Naval Shipbuilding Museum USS Salem (CA-139)
Answer: USS "Salem"