Ten years ago today, after years of planning and $1.2 billion, the A Line opened its sliding doors and whisked passengers out to the airport.
Looking back, that day — April 22, 2016 — summed up an era.
Colorado’s population was growing at one of its fastest paces ever. The state added more than 83,000 people; 2015 and 2016 were the most explosive years of a decade of growth.
The completion of the A Line represented a major milestone for the airport and the FasTracks transit system, two of the biggest investments in a series of projects that changed the city.
The idea of a train to the plane had been floating around since the 1980s, when our faraway airport was still in planning. A report from 1988 lays out early plans for a train to “the New Denver Airport” that would run alongside the future Peña Boulevard.
On opening day, long lines of passengers waited to board the new trains, which could reach 79 mph — much faster than the light-rail lines that preceded it. It was one of several new lines to open in the late 2010s, marking the last big expansion of RTD.
It wasn’t all excitement on opening day: Due to problems with the timing of crossing arms, the trains had to blare their horns at every single crossing for years, until 2019. It drove people nuts, and there was a big lawsuit.
A decade later, what has changed?
The airport train quickly became the most popular rail line in the system. It is more than twice as popular as the E Line
But along with the rest of RTD and perhaps the city itself, the A Line has been in low-growth mode.
In 2019, the train saw up to 736,000 boardings per month. In 2025, the peak month saw just about 647,000 boardings. That happened even as the airport set traffic records — a result of a broader shift in how people get around.
One common complaint: It costs $20 per person for a round trip to the airport. For a family of four, it’s often cheaper to simply drive and park at a shuttle lot.
That goes to one of the big debates facing the RTD board: They want to grow ridership and recover from the pandemic crash. But the agency faces a fiscal crisis that makes it tough to lower prices or improve service.
There’s also the question of the next airport transportation project. The city is preparing to spend big on an expansion of Peña Boulevard to the airport, but transit advocates want the city to consider improvements to bus and train systems.
The advocacy group Greater Denver Transit has suggested changes like buying double-decker trains to increase capacity, or “double tracking” sections of the line to allow more frequent service. The group also wants to see better bus service.
For now, those will stay on the wishlist.
Happy birthday to us
Coincidentally, Denverite launched around the same time as the A Line. One of our first newsletter headlines was “Train to the plain,” which might have been a typo but also became a great pun about the airport’s home in the tall grass.
Anyway: Our 10th birthday is soon, too. Subscribe to our newsletter to get a heads up about the party.
