Rancho San Luis Gonzaga was a Mexican land grant in the Diablo Range, in present-day Santa Clara County and Merced County, California given in 1843 by Governor Manuel Micheltorena to Juan Perez Pacheco and José Maria Mejía. The grant was bounded by Francisco Pacheco's Rancho Ausaymas y San Felipe on the west (at the top of present-day Pacheco Pass), the San Joaquin River and San Joaquin Valley on the east, and Los Baños Creek on the south.