What do you think Alberto Rios means when he says theat Mexico is green and the US blue paragraph 9?

Alberto Rios makes a parallel between the colors green and blue and the cultures prevailing in Mexico and the US.

While in the US the prevailing color is blue, as hinted by phrases such as "blue jeans", "blue laws" and "feeling blue", in Mexico the prevailing color is green, in accordance with phrases like "green corn", "green light", "greener on the other side".