[5] A formal Alternatives Analysis study conducted in 2004–2005, which included extensive community and citizen involvement, identified the proposed rail line as the best and most cost-effective mobility solution for Denton County and the region.

It cited the impacts of projected population growth, growing safety, traffic congestion and air quality concerns, as well as the need to improve access to Denton County's vital health care facilities and three major college and university campuses.

In May 2005, the DCTA Board of Directors approved the study's recommendation to construct the rail alignment on east side of I-35E using an existing railroad corridor.

DCTA's then-director of transportation services, Dee Leggett, stated that the A-train name "represent[s] Denton's position as the apex of the Dallas/Fort Worth region.

[14][1] On November 3, 2020, Rio Grande Pacific assumed the operations of the A-train for the remainder of the contract and partnered with Stadler US for the maintenance of rolling stock.

[1] The North Central Texas Council of Governments Mobility 2045 plan calls for the A-train to be extended south to interchange with the DART Silver Line.

[20] The A-Train began operations using 10 Budd RDC-1s leased from Trinity Railway Express, which were used until DCTA's own purpose-built fleet was delivered.