The 1870's and 1880's saw more lines spring up, reaching off to such exotic places as Hall's Springs (Montebello), Pikesville, Towson, and Powhatan (Woodlawn), but as the 1880's reached the midpoint, new emphasis was placed not on the locations to be served, but rather the motive power to serve them. Professor Leo Daft, in 1885, began an experiment on the Baltimore & Hampden lines to use electric power to propel former horsecars along the rather steep and curving line between 40th & Roland and Oak (Howard) & 25th Streets. Power was supplied through a third rail laid between the riding rails that supplied power to a locomotive pulling a horsecar. Although the success of the line is debatable, it is known that the line reverted to horse power in 1889, as the electrical equipment used by the line wore out. Still, the experiment did point the way towards the future, and changes were in store for Baltimore's transit.

Cable cars and electric trolley cars both debuted around the dawn of the1890's. Although there were already concerns as to expense involved in constructing and maintaining cable propulsion systems, there was a general disgust amongst the public for overhead lines being constructed in the Downtown area, as they were already in abundance, and were in the process of being relegated to culverts, so while the North Avenue Railway (whose service began on May 16, 1890) was able to construct an expanding trolley line along the Northern outskirts of town, Baltimore Traction Company and City Passenger were left to the expensive task of constructing cable lines to serve the central areas of the city. Cable sevice began on May 23, 1891 and was an instant success if only for its novelty. However, upcoming overhead lines began to encroach on the city's center in 1892, and by May of 1893, had entered the Downtown area by means of an elevated structure above Northern Central's rail yards along North Street (Guilford Avenue). Finally, the stage was set for the shape of things to come, as the cable lines were rather swiftly converted to the overhead electric system of propulsion, and the duration of the 1890's was spent constructing and converting lines to the new format, with the last horses pulling cars about 1902 on the Lorraine Cemetery line.

As the new century was dawning, the focus shifted to the companies themselves, which had consolidated into three companies in 1898, and then into one by the start of 1900. The United Railways and Electric was formed as the sole provider of electric streetcar transportation in the city. The 1900's saw the extension and expansion of service even further, as well as the construction of several impressive new facilities to house and maintain the growing fleet of streetcars. For a while, the picture for Baltimore's transit seemed pretty optimistic, but challenges were on the way, and would change the course of events for the coming decades. The biggest of these challenges came in a small package known as an automobile.

The 1910's were a tumultuous decade for the city's growing transit system. Introduction of more economical gas-powered automobiles began to eat away at the ridership of the city's streetcars. As if that weren't enough, "jitneys:" small, but versatile buses, began to be run by independent operators, further stifling the UR&E's ability to grow. These changes were not instant, however, as the system did see some expansion, and it even tried to fight the jitneys off, by forming its own bus franchise, called the "Baltimore Transit Company." The advent of the first World War caused tremendous surges in streetcar ridership, much of which the UR&E was unprepared for, as the availability of new cars was rationed by the government.

As the "Roaring 20's" progressed, the streetcars continued to fall out of favor with the public, whose prosperity in these times, allowed many of them to purchase their own autos. Buses began to make further inroads as well, as lines on Charles and Fayette streets were meeting with increasing success. A "railless car" Trackless Trolley line was also experimented with as well, lasting nearly nine years. Aside from two demonstrator cars purchased in 1924, and a fleet of small "Birney Cars" used on peripheral lines, the UR&E did not purchase any new cars between 1919 and 1930. Ridership continued to fall, and only worsened on the advent of "The Great Depression" in 1929, as many working class riders found themselves out of their jobs.

The UR&E's woes worsened into the 1930's, and in 1935, the Baltimore Transit Company (BTC) was formed to try to resurrect the ailing transit system. At first, the system began a balanced approach to investing in the purchase of new buses and streetcars, as well as trackless trolley coaches, a hybrid of the two modes. Studies were conducted to try to evaluate the best modes for each individual line, and modernization and expansion were stressed to be able to remain competitive in the difficult environment.

BTC's biggest shot in the arm came in 1941, when the US entered World War II. Anticipating the call to arms, BTC had wisely stored its retired streetcars instead of scrapping them, so it was better prepared for the effort than UR&E had been in WWI. Rubber and gasoline were precious items to the war effort, so they were rationed, forcing a massive number of the public back to the rails for their commutes. No new buses were able to be ordered from 1942 until mid-1945, but the company was able to secure a number of modern streetcars during this time, as well as a handful of extra trackless trolleys. The profits realized by the wartime years were short lived however, and attitudes on public transit quickly changed in the years following the war. The control of the BTC by out of town interests concerned with the Auto, Tire, and Petroleum industries did not help matters at all either, as the comprehensive rail network was almost entirely dismantled in a mere ten years.

In the 1950's, the decentralization of the metropolitan area, caused to futher bleed the heart of the transit system dry. While the BTC continued to convert rail lines to bus lines (with a few conversions to Trackless Trolley), with the support of Traffic Engineer Henry Barnes, in its efforts to save money by avoiding necessary infrastructure investments, the public continued to abandon the lines for the convenience of their automobiles. By 1955, only five lines remained to be operated by streetcars, along with a minor rail shuttle that was converted before year's end. By 1959, this number was down to only two, albeit among the heaviest routes in the system. Buses had replaced the rest of the routes, if in fact they weren't abandoned, as the system tried a desperate effort to reach out into the ever expanding suburbs in its attempts to regain lost business. Six trackless lines that had existed at the start of 1956 were all converted by mid-1959 as well.

Therefore, as the 1960's dawned, the BTC was in the midst of its own downward spiral. They had desired to convert the remaining two rail lines to bus, but did not have enough capital to purchase replacement buses and repave the streets as well. Thus, the streetcars hung on until November 3, 1963, at which point the system became entirely operated by buses. However, the buses were no more successful (if not less so) at regaining ridership to the Baltimore system. BTC had grappled with labor strikes throughout this period, and each one only detered the remaining ridership on the system. By the late 1960's, it had become obvious that transit was never going to be a lucrative, profitable venture, and State takeover became imminent. It was only a matter of time

The Metropolitan Transit Authority (later renamed the Mass Transit Administration, always referred to as the "MTA") took over the operation of the BTC on April 30, 1970, and began a modernization program just as the BTC had done 35 years earlier. MTA purchased new buses and absorbed the operations of many small suburban carriers as well, to expand its service as far Southward as Annapolis. The system's expansion, as well as an energy crisis in the mid-1970's did help to boost ridership in the early years. As a result, further expansion continued, largely in the form of Park & Ride services to try to lure commuters from their cars.

The 1980's saw periods of expansion and contraction, as in 1982, MTA purchased its first wheelchair-lift equipped buses to accomodate persons with disabilities. In 1983, the Baltimore Metro subway line opened its first phase, returning rails to the city's transit picture for the first time in twenty years. The Metro was extended over its second phase in July of 1987, heading to Owings Mills. But as the 1980's began to draw to a close, a tough economic environment saw the discontinuance of many marginal bus services. This trend continued into the early 1990's, combined with fare increases to cover escalating operating costs.

The 1990's saw a number of changes as well. In 1992, streetcars retuned to Baltimore in the form of new light rail vehicles running from Timonium to Camden Station, later to be extended several times. A final addition was made to the subway line to extend service in 1995 to Johns Hopkins Hospital. And in 1996, the fare structure was changed to eliminate the transfer, as the $3.00 All-Day Pass was initiated. The changes of the 1990's have met with some success. Bus ridership is growing at a slight rate, and the light rail line is measured as a success as well. MTA's commuter rail arm, known as MARC, is trying to build upon a faithful following as well, and at the advent of this new millenium, Baltimore's transit is holding its own for the time being, and doing a pretty good job at it.