JACKSON, Miss. — As the sun bore down around 2:15 p.m. on Wednesday, Dale Gibson began affixing signs to the iron fence surrounding Mississippi’s only abortion clinic. “The fight is not over,” one read. In cursive script, another vowed: “This is not the end.” Wednesday was the last day the Jackson Women’s Health Organization was legally allowed to perform abortions in Mississippi. It was the last day Gibson and his fellow volunteer patient escorts gathered outside the clinic to defend a right that no longer exists in much of the country. For years, the volunteers — known as the Pink...