Even in this era of jet travel, the sound of a train whistle at night retains a mystical pull, tugging us back to a past when railroads were the way Americans crossed the country. Trains carried both a restless, growing population and commercial goods across vast and swaths of land. Some of that land was inhabited by Native American tribes, whose displacement was hastened by the construction of the railroad. For better or worse, it is little exaggeration to say that the industrialized nation we know today was built on rails of iron.

A landmark moment in that history came on May 10, 1869, when the Central Pacific and Union Pacific Railroads met at Promontory Summit in the Utah Territory. Officials drove four ceremonial spikes, including at least one made of gold, to join the two lines and create the nation’s first transcontinental railroad. “It was built to tie the nation together,” says Wendell Huffman, curator of history at the Nevada State Railroad Museum in Carson City, Nevada.

The 150th anniversary of that momentous event will be celebrated this May at Golden Spike National Historical Park at Promontory Summit, which Leslie Crossland, site superintendent, refers to as “the little park with a great big story.” The festivities will include interpretive displays and activities telling the broader story of the various cultural groups who worked to complete the railroad. The site contains replicas of the two steam locomotives that met on the rails 150 years ago, and on weekends throughout the summer, re-enactors will portray the driving of the golden spike.

As many as 15,000 Chinese workers toiled to build the First Transcontinental Railroad, working in dangerous, harsh conditions while facing pervasive prejudice. Their critical contribution to the line will be recognized with the Chinese Railroad Workers Memorial, planned for late 2019 or early 2020 at a site off Interstate 80 near Gold Run, California. The centerpiece will be a statue, created by Chinese artist Xuejun Yang, that captures the backbreaking work of Chinese men who carved the railroad’s course—sometimes through solid granite.

Madison’s estate includes an extensive exhibit on slavery and its lasting effect on U.S. culture, and the restored 1910 station’s authentic period details reflect that legacy: lettering above doorways to designate the separate waiting rooms for whites and African Americans during the era of Jim Crow segregation.

The Mount Washington Cog Railway, which carries visitors to the top of the highest peak in the Northeast, is also celebrating its 150th anniversary this year. Since July 3, 1869, the railway near Bretton Woods, New Hampshire, has ferried visitors to Mount Washington’s 6,288-foot summit, where they enjoy hiking trails, vistas stretching for miles, and a 166-year-old former hotel called the Tip Top House. Invented by Sylvester Marsh, the railcars use an -ingenious “rack-and-pinion” design that engages the tracks like the teeth of a bicycle gear to climb the steep grade, an approach recognized as a Historic Civil Engineering Landmark by the American Society of Civil Engineers.

When Americans still primarily traveled cross-country by rail, many booked a berth in a Pullman sleeping car for longer trips. The Pullman Palace Car Company leased its luxurious cars to railroads and operated them, and in 1880, founder George Pullman created one of the nation’s first planned company towns. Today, the Pullman National Monument in Chicago, also part of the National Treasures program, preserves the innovative urban design and architecture of that community, including part of the factory as well as the historic Hotel Florence.

The monument also includes the National A. Philip Randolph Pullman Porter Museum, which tells the story of the Brotherhood of Sleeping Car Porters, the first African American union to be nationally recognized.

Seattle’s King Street Station combines a Beaux-Arts building with an Italianate clock tower that was the city’s tallest structure when it opened in 1906. The 242-foot tower was modeled on the Campanile di San Marco in Venice and features four large mechanical clocks built by E. Howard & Company of Boston. (A new motor was added to power the clocks’ mechanisms.) The station, placed on the National Register in 1973, had fallen into disrepair before it was restored by the city in 2013. A historic gateway to the Pacific Northwest, it still serves as a terminus for Amtrak’s Empire Builder train from Chicago and the Coast Starlight from Los Angeles.

*This story was updated on May 13, 2019.