It depends on what country we're talking about. In many areas of south america, Rural areas have no access to sanitation or clean water or, in some cases, advanced medical institutions. However, in the USA, population health in cities is worse than at the national level. In NYC, the evidence is incontrovertible: life expectancy at birth is lower than in the U.S. as a whole, particularly for males (67.8 years); infant mortality (IM) is higher; and rates of "feeling worse", self-reported total mobility limitations among persons 65 years and older (18.1%) are higher than for New York State overall (16%). In Tokyo, however, there are no significant differences, along these measures, in comparison to Japan. In Paris, although there are no differences in LEB when compared to France as a whole, infant mortality is lower in Paris than in France (4.0 vs. 4.6). And in London, although there are no significant differences in IM, or in LEB for men, women have a longer LEB (79.3) than in the UK as a whole (78.8).
I totally ripped most of that data off of some website.