suburban bus operators over the following two decades. Many routes have been modified during the MBTA era; the agency introduced crosstown routes in 1994 and the Silver Line in 2002. History A number of horsecar lines were built in Boston and surrounding towns in the second half of the 19th century, beginning with the Cambridge Railroad in 1856. Several smaller companies were consolidated into the West End Street Railway in 1887. The West End began electrifying existing lines and constructing new streetcar lines; the last horsecar lines ended in 1900. The West End was purchased in 1897 by the Boston Elevated Railway (BERy), which had been created to build a rapid transit system in Boston. As that system was constructed in the first two decades of the 20th century, many streetcar lines were cut back from downtown Boston to rapid transit stations. Stations like , , , , and were built as transfer stations with easy connections between subway and rapid transit. Some small companies operated buses in Boston as early as the 1910s. BERy bus service began on February 23, 1922, when buses replaced the North Beacon Street streetcar line. Initial bus routes largely replaced lightly-used streetcar lines or expanded service to new areas. The BERy also attempted in the 1920s to make the Tremont Street streetcar subway operate more like a rapid transit line, using trains of streetcars entering the subway from a small number of feeder lines, rather than single streetcars from numerous surface lines. The Harvard–Lechmere streetcar line was converted to trackless trolley (trolleybus) on April 11, 1936 – the first route in what would become an extensive trackless trolley system. As increased automobile usage reduced ridership and increased congestion, the BERy and its 1947 replacement Metropolitan Transit Authority (MTA) continued to convert streetcar lines to bus and trolleybus. Most trolleybus lines were replaced by buses in the late 1940s to early 1960s, as buses offered increased flexibility and no need to maintain overhead lines. When the Massachusetts Bay Transportation Authority (MBTA) replaced the MTA in 1964, all surface lines were operated by buses except six streetcar lines (the five Green Line branches plus the Mattapan Line) and four trolleybus lines. The MBTA rebranded many elements of Boston's public transportation network in its first decade. After being found unsuitable in 1965 for the Orange Line because it did not show up well on maps, yellow was