The old elevated railways proved to be an eyesore and required several sharp curves in Boston's twisty streets.
The Atlantic Avenue Elevated was closed in 1938 amidst declining ridership and was demolished in 1942.
As rail passenger service became increasingly unprofitable, largely due to rising automobile ownership, government takeover prevented abandonment and dismantlement.
The MTA purchased and took over subway, elevated, streetcar, and bus operations from the Boston Elevated Railway in 1947.

In the 1950s, the MTA ran new subway extensions, while the last two streetcar lines running into the Pleasant Street Portal of the Tremont Street Subway were substituted with buses in 1953 and 1962.
In 1958 the MTA purchased the Highland Branch from the Boston and Albany Railroad, reopening a year later as rapid transit line (now the Green Line D branch).

While the operations of the MTA were relatively stable by the early 1960s, the privately operated commuter rail lines were in freefall.
The New Haven Railroad, New York Central Railroad, and Boston and Maine Railroad were all financially struggling; deferred maintenance was hurting the mainlines while most branch lines had been discontinued.
The 1945 Coolidge Commission plan assumed that most of the commuter rail lines would be replaced by shorter rapid transit extensions, or simply feed into them at reduced service levels.
 Passenger service on the entire Old Colony Railroad system serving the southeastern part of the state was abandoned by the New Haven Railroad in 1959, triggering calls for state intervention.
Between January 1963 and March 1964, the Mass Transportation Commission tested different fare and service levels on the B&M and New Haven systems.
Determining that commuter rail operations were important but could not be financially self-sustaining, the MTC recommended an expansion of the MTA to commuter rail territory.

On August 3, 1964, the MBTA succeeded the MTA, with an enlarged service area intended to subsidize continued commuter rail operations.
The original 14-municipality MTA district was expanded to 78 cities and towns.
 Several lines were briefly cut back while contracts with out-of-district towns were reached, but, except for the outer portions of the Central Mass Branch (cut back from Hudson to South Sudbury), West Medway Branch (cut back from West Medway to Millis), Blackstone Line (cut back from Blackstone to Franklin), and B&M New Hampshire services (cut back from Portsmouth to Newburyport), these cuts were temporary; however, service on three branch lines (all of them with only one round trip daily: one morning rush-hour trip in to Boston, and one evening rush-hour trip back out to the suburbs) was dropped permanently between 1965 and 1976 (the Millis (the new name of the truncated West Medway Branch) and Dedham Branches were discontinued in 1967, while the Central Mass Branch was abandoned in 1971).
 The MBTA bought the Penn Central (New York Central and New Haven) commuter rail lines in January 1973, Penn Central equipment in April 1976, and all B&M commuter assets in December 1976; these purchases served to make the system state-owned with the private railroads retained solely as operators.
 Only two branch lines were abandoned after 1976: service on the Lexington Branch (also with only one round trip daily) was discontinued in January 1977 after a snowstorm blocked the line, while the Lowell Line's full-service Woburn Branch was eliminated in January 1981 due to poor track conditions.

The MBTA assigned colors to its four rapid transit lines in 1965, and lettered the branches of the Green Line from north to south.
 Shortages of streetcars, among other factors, caused bustitution of rail service on two branches of the Green Line.
 The A branch ceased operating entirely in 1969 and was replaced by the 57 bus, while the E branch was truncated from Arborway to Heath Street in 1985, with the section between Heath Street and Arborway being replaced by the 39 bus.

The MBTA purchased bus routes in the outer suburbs to the north and south from the Eastern Ma
The old elevated railways proved to be an eyesore and required several sharp curves in Boston's twisty streets. The Atlantic Avenue Elevated was closed in 1938 amidst declining ridership and was demolished in 1942. As rail passenger service became increasingly unprofitable, largely due to rising automobile ownership, government takeover prevented abandonment and dismantlement. The MTA purchased and took over subway, elevated, streetcar, and bus operations from the Boston Elevated Railway in 1947.
In the 1950s, the MTA ran new subway extensions, while the last two streetcar lines running into the Pleasant Street Portal of the Tremont Street Subway were substituted with buses in 1953 and 1962. In 1958 the MTA purchased the Highland Branch from the Boston and Albany Railroad, reopening a year later as rapid transit line (now the Green Line D branch).
While the operations of the MTA were relatively stable by the early 1960s, the privately operated commuter rail lines were in freefall. The New Haven Railroad, New York Central Railroad, and Boston and Maine Railroad were all financially struggling; deferred maintenance was hurting the mainlines while most branch lines had been discontinued. The 1945 Coolidge Commission plan assumed that most of the commuter rail lines would be replaced by shorter rapid transit extensions, or simply feed into them at reduced service levels.  Passenger service on the entire Old Colony Railroad system serving the southeastern part of the state was abandoned by the New Haven Railroad in 1959, triggering calls for state intervention. Between January 1963 and March 1964, the Mass Transportation Commission tested different fare and service levels on the B&M and New Haven systems. Determining that commuter rail operations were important but could not be financially self-sustaining, the MTC recommended an expansion of the MTA to commuter rail territory.
On August 3, 1964, the MBTA succeeded the MTA, with an enlarged service area intended to subsidize continued commuter rail operations. The original 14-municipality MTA district was expanded to 78 cities and towns.  Several lines were briefly cut back while contracts with out-of-district towns were reached, but, except for the outer portions of the Central Mass Branch (cut back from Hudson to South Sudbury), West Medway Branch (cut back from West Medway to Millis), Blackstone Line (cut back from Blackstone to Franklin), and B&M New Hampshire services (cut back from Portsmouth to Newburyport), these cuts were temporary; however, service on three branch lines (all of them with only one round trip daily: one morning rush-hour trip in to Boston, and one evening rush-hour trip back out to the suburbs) was dropped permanently between 1965 and 1976 (the Millis (the new name of the truncated West Medway Branch) and Dedham Branches were discontinued in 1967, while the Central Mass Branch was abandoned in 1971).  The MBTA bought the Penn Central (New York Central and New Haven) commuter rail lines in January 1973, Penn Central equipment in April 1976, and all B&M commuter assets in December 1976; these purchases served to make the system state-owned with the private railroads retained solely as operators.  Only two branch lines were abandoned after 1976: service on the Lexington Branch (also with only one round trip daily) was discontinued in January 1977 after a snowstorm blocked the line, while the Lowell Line's full-service Woburn Branch was eliminated in January 1981 due to poor track conditions.
The MBTA assigned colors to its four rapid transit lines in 1965, and lettered the branches of the Green Line from north to south.  Shortages of streetcars, among other factors, caused bustitution of rail service on two branches of the Green Line.  The A branch ceased operating entirely in 1969 and was replaced by the 57 bus, while the E branch was truncated from Arborway to Heath Street in 1985, with the section between Heath Street and Arborway being replaced by the 39 bus.
The MBTA purchased bus routes in the outer suburbs to the north and south from the Eastern Ma
Massachusetts Bay Transportation Authority