According to this chart from HuffPo, the US Presidential race is very close. Look at the two trend lines, close together, both just a little under 50%:
But wait—according to this chart from HuffPo, Obama has an enormous lead! Look at this huge gap! Obama's trend line is nearly off the chart!
As you've no doubt figured out by reading the title of this post, they are in fact the same chart; it's just that one has a y axis that goes from 0% to 100%, while the other has a y axis that goes from 42% to 49%.
The latter is more dramatic, and shows the differences more clearly, and so people tend to show graphs more like the latter than like the former. HuffPo's default view, for example, has a y axis running from 35% to 55%:
And that's not a false view of the data; it's arguably not even misleading, given that a lead of a few percentage points is significant in this race. But I do think it's always worth checking the y axis to see just what the graph is really showing.