Murphy, TX. Murphy is a city in Collin County, Texas, United States and a suburb of Dallas, located to the north east of the city. The 2010 census reported Murphy's population as 17,708. Murphy is a fast-growing community with a history that goes back to the early 1900s. Murphy is located in southern Collin county, within the Dallas/Fort Worth metroplex. Situated midway between Plano and Wylie on FM 544, Murphy is two miles (3 km) south of the famous Southfork Ranch. Its borders enclosing only 3.8 square miles (9.8 km2), Murphy shares borders with Plano, Richardson, Wylie, Sachse, and Parker.