When Pope Francis addressed Congress in 2015, he cited four great Americans: President Abraham Lincoln, civil rights leader Martin Luther King Jr., writer and activist Dorothy Day and theologian Thomas Merton. Ms. Day, who died in 1980 at age 83, was a remarkable 20th century figure: journalist and founder of the “Catholic Worker” movement, which established soup kitchens and “houses of hospitality” in the Great Depression. More than 200 Catholic worker facilities remain in operation today.