Throughout its decades-long planning process, the project was dogged by resistance, particularly from residents of the upscale community of Chevy Chase and members of the Columbia Country Club.

From 2003 to 2006, Maryland Governor Robert Ehrlich changed the proposed mode of transportation from light rail to bus rapid transit.

[9][10] In 2016, a consortium headed by Fluor Enterprises won the $5.6 billion contract to design and build the Purple Line, then to operate and maintain it for 36 years.

[12] Work halted in September 2020, when the consortium withdrew from the contract, citing mounting delays and disputes with the state government.

[22] In 1987, after CSX expressed a desire to abandon the Georgetown Branch rail line, Maryland leaders immediately started planning to repurpose it for transit and a hiking trail.

The GBLRT was proposed as a light rail transit line from Silver Spring westward, following the former Georgetown Branch of the Baltimore and Ohio Railroad, now a short CSX siding and the Capital Crescent Trail, to Bethesda.

[30] In January 2008, the O'Malley administration allocated $100 million within a six-year capital budget to complete design documents for state approval and funding of the Purple Line.

To make up the difference, Prince George's and Montgomery counties would contribute more money and the frequency of train service would be reduced.

On December 7, 2015, four teams composed of major American and international firms submitted their bids to realize the project:[63][64] On March 2, 2016, Hogan announced that the state had chosen Purple Line Transit Partners to build, operate, and maintain the Purple Line for $3.3 billion over 36 years, with service to start in late 2022.

[67] Hogan responded that Leon's residence at the Columbia Country Club, a leading opponent of the line, represented a conflict of interest.

[67][69] On August 21, 2017, despite the ongoing court case over the environmental analysis, $900 million of federal funding was granted for the light rail project.

[10] This federal appeals court ruling allowed for construction to continue and effectively ended the three-year legal battle surrounding the light-rail line project.

[71] On April 13, 2020, U.S. District Judge James Bredar dismissed the third and final lawsuit brought by opponents of the Purple Line.

[72] By 2020, the project had accrued over $800 million in change orders from Purple Line Transit Partners and the opening date had slipped 32 months.

[73] A temporary restraining order halted the company from quitting work, but it was lifted in September,[76] and PLTP began packing up construction sites the following week.

[78] On November 24, MDOT agreed to pay $250 million to PLTP to settle the costs of overruns,[79][80] a move approved unanimously in mid-December by Maryland's Board of Public Works (BPW).

[19] In December 2024 it was reported that construction of the new mezzanine at the Bethesda station, a complex design, has led to extensive cost overruns.

[41] The new Woodrow Wilson Bridge (I-495's southern crossing over the Potomac River) is built to carry a heavy or light rail line.