A new U.S. postage stamp is triangle-shaped, and it’s valid on mail sent around the globe to more than 180 countries. The triangle Postcrossing stamp from the U.S. Postal Service commemorates an international pen pal project started in 2005 by Paulo Magalhães, a student in Portugal. The program connects people around the world in a simple but increasingly old-fashioned way: Send a postcard, get one back. What started as a website Magalhães hosted on his personal computer has since spread around the world. Today, more than 805,000 people from more than 200 countries and territories have sent more than 80 million postcards through the program. Americans have sent more postcards through Postcrossing than the residents of any country except Germany, but maybe a new stamp could put the U.S. on top. [Image: USPS] Postcrossing has gotten its own stamps before in countries including Germany and Finland . The U.S. Postcrossing stamps come following a letter-writing campaign by supporters to the USPS Citizens’ Stamp Advisory Committee, which recommends future stamps. Their successful letter-writing campaign also marks the return of a rare postage stamp shape. Most U.S. stamps are square- or rectangular-shaped , but in 1997, the USPS released its first triangle-shaped postage stamps , a pair of 32-cent stamps showing vintage-style illustrations of a clipper ship and stagecoach. Another, a 41-cent triangle stamp in 2007 , marked the 400th anniversary of the settlement of Jamestown, Virginia, by English colonists, and it was shaped like a triangle because that was also the shape of the fort they built there. [Image: USPS] The latest triangular stamps feature artwork by Arizona-based artist and designer Jackson Gibbs . Known for his editorial work in outlets like The New York Times and New York magazine, Gibbs says the creative brief for his first-ever stamps was to portray the activity of postcrossing (sending postcards), which he depicted in images in his playful, cartoon style. The four stamps he designed show people carrying mail on horseback through a Saguaro desert, underwater, in space, and by motorcycle. “The ideas came from things I like to draw over many years of culminated experience,” Gibbs tells Fast Company . The stamps were designed by USPS art director Antonio Alcalá. The U.S. Postal Service says the stamps recognize postcrossing for “promoting greater understanding across countries and cultures,” and it’s unveiling them at the Boston 2026 World Exposition from May 23 to 30 alongside stamps commemorating the American Revolution , the American bison, international peace, and North American soccer. The stamps come in sets of four or eight that fit together in a square, and they’re classified as Global stamps, which, like Forever stamps, hold the postage value equivalent of First-Class Mail no matter the cost of postage, except they can be used for international correspondence. First-Class Mail International is available in more 180 countries, including Canada, Great Britain, and Australia, according to the USPS. The official Postcrossing FAQ recommends writing on postcards about what daily life is like where you live, or about things like your favorite quote, a recipe, a childhood memory, or your favorite book, movie, band, or hobby. Bringing back triangle stamps for a program built on sending postcards makes smart design sense since they take up half the space of a rectangular stamp for a piece of mail without much room to spare. Now not only will Americans have more space for writing, but they’ll have a fun, friendly stamp to share with new friends around the world.