Methods for improving transportation between Montgomery and Prince George's counties have been under study since 1992 as part of the Capital Beltway and Purple Line studies. Planning and consideration for a transit facility along the Georgetown Branch right-of-way in Bethesda and Chevy Chase date back to the early 1970's and an east-west transportation link has been on the Montgomery County Master Plans for more than 20 years. The transitway along the Georgetown Branch and a line between Silver Spring and New Carrollton were combined as the Bi-County Transitway in 2003.
In early spring 2007, Secretary of Transportation, John Porcari, directed the MTA to restore the project to its former name, the Purple Line. While the Bi-County Transitway name reflected the two county area of the proposed project, the Purple Line was the original name for the project and had continued to be used by most people. The project study has not changed, and the Purple Line continues to be a high transportation priority.
In October of 2008 the Purple Line's Alternatives Analysis/Draft Environmental Impact Statement (AA/DEIS) was released. The AA/DEIS was available for public review for 90 days from October 17, 2008 to January 14, 2009. During this time, the MTA accepted and recorded public comments on the document and the project. These comments were taken into consideration when on August 4, 2009 Governor Martin O'Malley announced his selection of the Preferred Alternative (PA) for the Purple Line. This was a major milestone for the project and marked the completion of the AA/DEIS phase of the project.