In 1540 Hernando de Soto undertook an extensive exploration of the present US, developing expeditions in Georgia, The Carolinas, Tennessee, Alabama, Mississippi, Arkansas, Oklahoma, Texas and Louisiana; and in the same year Francisco Vásquez de Coronado led 2,000 Spaniards and Mexican Indians across today's Arizona–Mexico border. Coronado travelled as far as central Kansas, close to the exact geographic center of what is now the continental United States and he was the first European that saw the Canyon's Colorado. Other Spanish explorers of the US make up a long list that includes among others, Lucas Vásquez de Ayllón, Pánfilo de Narváez, Sebastián Vizcaíno, Juan Rodríguez Cabrillo, Gaspar de Portolà, Pedro Menéndez de Avilés, Álvar Núñez Cabeza de Vaca, Tristán de Luna y Arellano and Juan de Oñate. In all, Spaniards probed half of today's lower 48 states before the first English colonization attempt (Roanoke Island, 1585).