All of the 270+ presidential electors in the Electoral College from the enacting states will be supporters of the presidential candidate receiving the most popular votes among all 50 states (and DC)—thereby guaranteeing that candidate with an Electoral College majority.

95% of the U.S. population in 1790 lived in places of less than 2,500 people, and only a few states let males, with substantial property, vote.  It is unlikely that the Founders were concerned about presidential candidates being elected only by voters in big cities. 

Now, voters in the biggest cities in the US are almost exactly balanced out by rural areas in terms of population and partisan composition.

16% of the U.S. pop lives outside the nation's MSAs.  Rural America has voted 60% Republican. 

16% lives in the top 100 cities. They voted 63% Democratic in 2004. 

The rest of the U.S., in suburbs, divide almost exactly equally between Republicans and Democrats.