In 1955, at the age of 67, Gatewood told her grown children that she was going for a walk. They did not ask where or for how long, as they knew she was resilient and would take care of herself. About 5 years earlier, Gatewood read an article in National Geographic about the A.T. and thought "it would be a nice lark," though in retrospect considering the difficulty she added "It wasn't." The magazine gave her the impression of easy walks and clean cabins at the end of each day's expedition. Thus she took little in the way of outdoor gear. She wore Keds shoes and carried an army blanket, a raincoat, and a plastic shower curtain in a homemade denim bag slung over one shoulder. She would later say "For some fool reason, they always lead you right up over the biggest rock to the top of the biggest mountain they can find."
Local newspapers picked up on her story in the southern states, then the Associated Press did a national profile of her while in Maryland, leading to an article in Sports Illustrated when she had reached Connecticut. After the hike she was invited on the Today Show. These appearances made her a celebrity even before the hike was over and she was often recognized and received "trail magic" (assistance from strangers) in the form of friends, food and places to sleep.
She hiked the AT again in 1960, and then again at age 75 in 1963, making her the first person to hike the trail three times (though her final hike was completed in sections). She was also credited with being the oldest female thru-hiker by the Appalachian Trail Conference. In addition, she walked 2,000 miles (3,200 km) of the Oregon Trail from Independence, Missouri, to Portland, Oregon, averaging 22 miles (35 km) a day. She traveled to every state of the continental United States.
In 1970, at age 83, while visiting Appalachian Outfitters in Oakton, Virginia she was asked what she thought about the latest lightweight backpacking gear. Emma advised: "Make a rain cape, and an over the shoulder sling bag, and buy a sturdy pair of Keds tennis shoes. Stop at local groceries and pick up Vienna sausages... most everything else to eat you can find beside the trail... and by the way those wild onions are not called "Ramps"... they are "Rampions" ... a ramp is an inclined plane."
Gatewood was a life member of the National Campers and Hikers Association and the Roanoke Appalachian Trail Club. She was Director Emeritus and a lifetime member of the Buckeye Trail Association.