Question: James Fowle Baldwin helped design a historic railroad that operated in Massachusetts and whose line later operated as part of what?

Context:
Connecticut Southern Railroad
The Connecticut Southern Railroad (reporting mark CSOR) is a 78 mi long short-line railroad operating in Connecticut and Massachusetts, on lines originally operated by the New York, New Haven and Hartford Railroad, later operated by Penn Central and Conrail.
 It is a subsidiary of Genesee & Wyoming.
 The line is headquartered in Hartford, Connecticut and interchanges with CSX at West Springfield, Massachusetts and New Haven, Connecticut.
 Pan Am Railways exercises trackage rights to access its line at Berlin, Connecticut connecting to Waterbury, Connecticut.
Boston and Lowell Railroad
The Boston and Lowell Railroad is a historic railroad that operated in Massachusetts in the United States.
 It was one of the first railroads in North America and the first major one in the state.
 The line later operated as part of the Boston and Maine Railroad's Southern Division.
Florida Railroad
The Florida Railroad was the first railroad to connect the east and west coasts of Florida, running from Fernandina to Cedar Key.
 The line later became part of the Seaboard Air Line Railroad, and, where still in use, is operated by CSX Transportation and the First Coast Railroad.
 The highway corridor of SR 24, US 301, and SR A1A closely parallels the former Florida Railroad.
James Fowle Baldwin
James Fowle Baldwin (April 29, 1782 – May 20, 1862) was an early American civil engineer who worked with his father and brothers on the Middlesex Canal, surveyed and designed the Boston and Lowell Railroad and the Boston and Albany Railroad, the first Boston water supply from Lake Cochituate, and many other early engineering projects.
 He was the first president of the Boston Society of Civil Engineers and served one term as a Senator from Suffolk County to the Massachusetts Senate, then served as a Boston Water Commissioner.
Boston, Barre and Gardner Railroad
Boston, Barre and Gardner Railroad was a historic railroad that operated between Worcester, Massachusetts, Barre, Massachusetts and Gardner, Massachusetts, and its remaining functional tracks are now owned and operated by the Providence and Worcester Railroad (NASDAQ: PWX ).
Alabama and Vicksburg Railroad Depot
The Alabama and Vicksburg Railroad Depot is a historic railroad depot in Newton, Mississippi.
 It was located on the A & V (Alabama and Vicksburg) Railroad.
 It was built in 1904, and later operated by the Illinois Central.
 It was added to the National Register of Historic Places in 1990.
 It is now used by the Newton Chamber of Commerce.
Kansas Pacific Railway
The Kansas Pacific Railway (KP) was a historic railroad company that operated in the western United States in the late 19th century.
 It was a federally chartered railroad, backed with government land grants.
 At a time when the first transcontinental railroad was being constructed by the Central Pacific and the Union Pacific, it tried and failed to join the transcontinental ranks.
 It was originally the "Union Pacific, Eastern Division", although it was completely independent.
 The Pennsylvania railroad, working with Missouri financiers, designed it as a feeder line to the transcontinental system.
 The owners lobbied heavily in Washington for money to build a railroad from Kansas City to Colorado, and then to California.
 It failed to get funding to go west of Colorado.
 It operated many of the first long-distance lines in the state of Kansas in the 1870s, extending the national railway network westward across that state and into Colorado.
 Its main line furnished a principal transportation route that opened up settlement of the central Great Plains, and its link from Kansas City to Denver provided the last link in the coast-to-coast railway network in 1870.
 The railroad was consolidated with the Union Pacific in 1880, and its mainline continues to be an integral part of the Union Pacific network today.
George Rumford Baldwin
George Rumford Baldwin (North Woburn, January 26, 1798 – North Woburn, October 11, 1888) an early American civil engineer who worked with his father Loammi Baldwin and brothers Loammi Baldwin, Jr. Cyrus Baldwin, Benjamin Franklin Baldwin, and James Fowle Baldwin, on the Middlesex Canal and other projects.
 His later works included surveying and engineering the Boston, Hartford, and Erie Railroad, the Buffalo and Mississippi Railroad, and the gas and water systems for the City of Quebec.
Lowell Line
The Lowell Line is a railroad line of the MBTA Commuter Rail system, running north from Boston to Lowell, Massachusetts.
 Originally built as the Boston & Lowell Railroad and later operated as part of the Boston & Maine Railroad's Southern Division, the line was one of the first railroads in North America and the first major one in Massachusetts.
St. Louis, Peoria and Northern Railroad Depot
The St. Louis, Peoria and Northern Railroad Depot is a historic railroad station located at 1408 Broadway Street in Pekin, Illinois.
 The station was built in 1898 when the St. Louis, Peoria and Northern Railway built a line into Pekin; the railroad had formed only two years earlier as an amalgamation of ten other railroad companies.
 The new railroad provided direct passenger routes to Springfield, Illinois and St. Louis, Missouri and opened up better options for shipping freight north through Peoria.
 The depot became part of the Chicago & Alton Railroad in 1900 when it purchased the St. L. P. & N. line from Peoria to Springfield.
 The station served both passenger and freight traffic until passenger service ended in the 1930s; the railroad also served as an important part of Pekin's economy, both by employing residents and stimulating local industry.
 The station is one of the only historic rail-related buildings remaining in Pekin.

Answer: Boston and Maine Railroad's Southern Division