The Spanish "derivation" of the name is somewhat in doubt, as it is improper in the language to combine a masculine article with a feminine noun; it should be De La Rosa, since Rosa ends with an "a". However, there is little hope that this error can be rectified at this late date.
Del Rosa Post Office - 1945
According to Shibli Damus, the Indians named Del Rosa, after some of their Mexican friends told them the name of this flower in Spanish. Mr. Damus says that there was a local settlement of Indians in the foothills, and they built an adobe house on Del Rosa Avenue between 40th and Bonita Vista. When Mr. Damus bought the property in 1943, the house was 82 years old. He built the present structure around the Indian Adobe.
After a severe water shortage in the summers of 1952-1954, Del Rosa residents elected to become part of San Bernardino, but the area name remains today identifying the north-east portion of the city.