occurred during the Civil War. Delaware, though officially remaining a member of the Union, was a border state and divided in its support of both the Confederate and the Union causes. The war created enormous demand for goods and materials supplied by Wilmington including ships, railroad cars, gunpowder, shoes, and other war-related goods. By 1868, Wilmington was producing more iron ships than the rest of the country combined and it rated first in the production of gunpowder and second in carriages and leather. Due to the prosperity Wilmington enjoyed during the war, city merchants and manufacturers expanded Wilmington's residential boundaries westward in the form of large homes along tree-lined streets. This movement was spurred by the first horsecar line, which was initiated in 1864 along Delaware Avenue. The late 19th century saw the development of the city's first comprehensive park system. William Poole Bancroft, a successful Wilmington businessman influenced by the work of Frederick Law Olmsted, led the effort to establish open parkland in Wilmington. Rockford Park and Brandywine Park were created due to Bancroft's efforts. Both World Wars stimulated the city's industries. Industries vital to the war effort – shipyards, steel foundries, machinery, and chemical producers – operated around the clock. Other industries produced such goods as automobiles, leather products, and clothing. In desperate need of workers more and more minorities moved to the north and settled in places like Wilmington. This led to tensions that occasionally boiled over like the Wilmington, Delaware race riot of 1919. The post-war prosperity again pushed residential development further out of the city. In the 1950s, more people began living in the suburbs of North Wilmington and commuting into the city to work. This was made possible by extensive upgrades to area roads and highways and through the construction of Interstate 95, which cut through several of Wilmington's neighborhoods and accelerated the city's population decline. Urban renewal projects in the 1950s and 1960s cleared entire blocks of housing in the Center City and East Side areas. The Wilmington riot of 1968, a few days after the April 4 assassination of Martin Luther King Jr., became national news. On April 9, Governor Charles L. Terry, Jr. deployed the National Guard and the Delaware State Police to the city at the request of Mayor John Babiarz. Babiarz asked Terry to withdraw the National Guard the following week, but the governor kept them in the city