The popular vote for the Democratic candidates increased in a linear (or straight line) manner from 1972 to 2000 (excluding 1976). This linear increase has been deemed the "Democratic Trend Phenomenon."
 

During the same period of time the fluctuating popular vote for the Republican candidates from 1972 to 2000 (excluding 1976).
 

Because of the Democratic Trend, the Popular Vote% for the Democratic candidates and the combined "Non-Democratic" candidates tended to increase and decrease, respectively, in a linear fashion. By extending the trend lines the Democratic candidate, Senator Barack Obama is projected to obtain 51.1% (+/-2.7%) of the popular vote in 2008 while the Non-Democratic candidates (Senator John McCain plus the other Non-Majority Party candidates) divide 48.9% (+/-2.5%) amongst themselves.
 

The actual Democratic Popular Vote% for the Barack Obama was 52.6%. Thus, the projections using the Democratic Trend Phenomenon had an error of only 1.5%. This was astonishing considering that the projection could have been made in 2004.