There are some states (e.g. Vermont and Hawaii) which will vote for the Democratic presidential candidate almost without fail.
There are some states (e.g. Alabama, Utah, Alaska) which will vote for the Republican presidential candidate almost without fail.
The states where Democratic and GOP supporters are roughly equal (e.g. Florida) are considered "battleground states" because factors like the quality of candidates and the effectiveness of their campaigning strategies can actually influence the final outcome. Those states are a small fraction of the total number of US states (around 13-15 states, IIRC).
Trump wins another 4 electoral votes. The chances of that happening (and the reward to the GOP if it did happen) is so small that the GOP effectively concedes Hawaii to the Democratic Party. My understanding is political spending in "battleground states" dramatically dwarfs money spent in states which are considered "safe" for either major political party.
OldSchoolTheSKOSlives 