Holmes High School was once predomiantly anglo in 1960s and 1970s?

Al the schools in Northside and Northeast were almost entirely anglo in the 60s & 70s. It was economic segregation... minorities could simply not afford to live in those suburban areas. Loop 410 was the 'border' of the city back then and the anglo population mostly lived northeast and northwest of the downtown area. When I graduated from Robert E. Lee HS in 1970, there had never been a black student attend the school. About three years later, when I went back to attend my girlfreind's graduation, a pair of twin boys who were black graduated and received a standing ovation when they crossed the stage. Their father was a cardiologist and they moved into the area (Castle Hills, I believe) at the start of the Spring semester. It was several years before another black student attended Lee. Now, there are almost no anglo students there because of the changed demographics in the neighborhoods surrounding the school. The same situation was true at MacArthur, Churchill and Roosevelt in Northeast and at Holmes and John Marshall in the Northside district. John Jay was always highly minority because of its proximity to the military bases. Madison, Reagan and Johnson did not exist nor did Stevens, Clark or O'Connor.

Aggieband pretty much tells the story. Yes, your conjecture is correct.