This graph expresses the results of an opinion poll conducted by CNN in 2011. The poll was inquired about the opinions of Americans regarding the legality of same sex marriages in the United States.
We can see here that based on the results, since 1988 the American population has grown more in favor of the legalization of same sex marriages and has declined in opposition. For the first time ever, American proposition of same sex marriage is greater than the opposition.
Below is an image of CNN's sampling and collection of data for this poll. By viewing this we can see how different demographics (gender, race, age, education, region, etc.) tend to feel regarding same sex marriage in the United States.