This is impossible to truly answer. The number of voters is not consistent and varies from primaries to general elections and from presidential election years to off year elections. However, as we are on the cusp of a presidential election I can do my best to estimate how many voters we will have this year. In the 2000 election there were 105,586,274 votes cast and in 2004 there were 122,294,978 votes cast. If we project that same percentage of growth then we should see 141,647,783 votes cast. I believe the number will be higher though given the nature of this election.