A head to head comparison of the 2008 Nevada General Election gives us an idea of the break down of the voters.    

Barack Obama received 533,736 (55%) votes, beating John McCain who gained 412,827 (43%) by 120,909 votes in Nevada.

John McCain won 14 counties whereas Barack Obama won 3 counties in the total of the 17 counties in the State of Nevada.

Presidential General Elections

During the 2008 General elections, over 131M total number of votes were cast. Barack Obama got 69,448,278 (69.4 Million) over John McCain's 61,739,059 (61.7 Million). He won the popular vote by 7,709,219 (7.7 Million). His victory in the State of Nevada (with 533,736 votes) represents 0.8% of his popular vote victory. The remaining 49 states contributed to the remaining 99.2% popular votes victory.

Top 15 Counties Comparison in Primary Elections vs General Elections

All Candidates (General Elections)

These 15 counties play an important role in these Primary elections. If a candidate, can get a sizable majority in the largest counties (Clark, Washoe), it becomes very difficult to win majorities in the smaller counties without voter outreach and increased voter participation in them.

Top 15 Counties Comparison in Primary Elections vs General Elections

General Elections
Barack Obama

General Elections
John McCain

Clark, Carson City and Washoe, three of the larger counties voted in favor of Barack Obama, giving him a 146K vote advantage. However, steady marginal wins for John McCain in all the other counties were not enough to overcome that deficit, making Barack Obama gain an upper hand in the State of Nevada.

Related References: 2016 Nevada Primary Election Story, 2016 Nevada General Election Story, 2020 Nevada Primary Election Story, 2020 Nevada General Election Story, 2012 Nevada General Election Story