What is the tone for 少 in 老少边穷地区? I hear Mr. Xi Jinping in his address to villagers spoke 老少边穷地区 in the fourth tone (i.e., 少 as 绍）, but I think he might have made a mistake here, out of instincts, without any real understanding.
Here’s 现代汉语规范词典’s entry:

老少边穷
PY lǎo-shǎo-biān-qióng
老解放区､少数民族地区､边疆地区和穷困地区的合称。
注意 “少”这里不读shào, 不当“年少”讲。