This article was first published on May 1, 2011 for Amtrak's 40th birthday. We're sharing it again today with a few updates to celebrate its 48th.

Today, Amtrak turns 48. This slideshow shows how passenger rail service has evolved over the decades, using maps from Malcolm Kenton and the National Association of Railroad Passengers.

On May 1, 1971, Amtrak replaced a much more extensive private passenger rail network that was on the decline due to massive government investment in other modes of transportation. It has struggled at times throughout its 48-year history, and some routes have come and gone, but it’s kept valuable rail service alive.

What remains of the national passenger train network, albeit skeletal compared to what it was and what it should be, exists largely thanks to the efforts of grassroots advocates who understand trains’ superior energy efficiency and the importance of having balance and choice in the American transportation system.

The National Association of Railroad Passengers (NARP) organized in 1967 and built a broad coalition that lobbied successfully for the passage of the 1970 law that created Amtrak. NARP and its allies have successfully fought further contraction of the system ever since, and are now building support for long-term, dedicated federal funding for intercity passenger rail—something highways and aviation enjoy, while Amtrak has had to fight for its small share of general funds in every year’s appropriations cycle.

David Alpert is Founder and President of Greater Greater Washington and Executive Director of DC Sustainable Transportation (DCST). He worked as a Product Manager for Google for six years and has lived in the Boston, San Francisco, and New York metro areas in addition to Washington, DC. He lives with his wife and two children in Dupont Circle. Unless otherwise noted, opinions in his GGWash posts are his and not the official views of GGWash or DCST.

Malcolm Kenton lives in the DC’s NoMa neighborhood. Hailing from Greensboro, NC and a graduate of Guilford College (BA) and George Mason University (MA, Transportation Policy), he is a consultant and writer on transportation, travel, and sustainability topics and a passionate advocate for world-class passenger rail and other forms of sustainable mobility and for incorporating nature and low-impact design into the urban fabric. The views he expresses on GGWash are his own.