In 1942, Gertrude Chandler Warner, a Connecticut grade school teacher, unveiled The Boxcar Children, her first book—she wrote 18 more—in what would become a cherished series of more than 150 titles. Since the 1960s, Albert Whitman & Company has been publishing the Boxcar Children, and for the series’ 75th anniversary, the artwork attached to the precocious, mystery-solving Alden brood has taken a contemporary turn.

In celebration of this year’s milestone, there is a new five-book collection, the Boxcar Children Great Adventure, guided by a continuous arc that takes the siblings to glamorous locales around the globe in search of rare, stolen artifacts. And the fall brings a refreshed, 20-book set, including all the titles written by Warner, that will further amplify the Boxcar Children’s present-day appeal, bolstered by an animated film adaptation of Warner’s second book, Surprise Island.

When The Boxcar Children debuted, illustrator L. Kate Deal’s art “reflected the era and the story perfectly in their simplicity and wholesomeness,” says Albert Whitman’s creative director, Jordan Kost. “This timeless design also underscores the books’ content about the family. One of the most interesting things about the books is that they’re not terribly action-packed, like what you’d expect in a modern adventure story. They’re more like quiet observations of the Aldens going about their daily lives and taking care of one another. But it’s also what has given them such longevity. Even though the clothing they’re wearing looks different and the technology isn’t there, kids today can still relate to them because they are simply kids being kids.”

The new books now flaunt colorful covers courtesy of illustrator Anthony VanArsdale, and are branded with a fresh logo that still has nostalgic undertones—“you can’t quite put your finger on whether it’s the original or if it’s completely new,” says Kost. In the Boxcar Children Great Adventure books, VanArsdale’s images depict the Aldens stepping off a private train in New Mexico, riding camels through the Egyptian desert, passing by elephants in a tuk-tuk in Thailand, landing in snowy Antarctica via a helicopter, and taking in the spectacle of Machu Picchu. Giving a distinct visual identity to each of the protagonists was essential, Kost says, to the books’ leap into modernity. This process was simplified, she says, by Warner’s “mindfulness in developing four unique characters, each with their own personalities and strengths. All that we needed to do was build upon what was there, enhance it, and, of course, add smartphones.”