Use summarize to determine the number of counties in each state that lost population.

  b.

there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.