It's no secret that marriage rates in the U.S. are declining, but sometimes you have to see things to believe them.

Using data from the Centers for Disease Control and Prevention and U.S. census, researchers at Movoto -- a real-estate blog dedicated to data crunching -- created this gif that demonstrates the fall in marriage rates by state from 1970 to 2011. (You'll notice that Nevada is singled out, as its marriage rates are drastically higher than the rest of the country).

While researching marriage rates, Movoto went one step further and split the data into two time periods: 1970-2003 and 2004-2011. "We selected 2004 as a boundary because it was the first year that gay marriage took effect in a U.S. state ( Massachusetts)," Movoto explained in their report.

Their goal in doing so was to determine whether or not same-sex marriage is to blame for falling marriage rates, as some religious conservatives may postulate.

According to the numbers, same-sex marriage had no effect on declining marriage rates whatsoever. Twenty-four states saw faster declining marriage rates after 2004, but 25 states plus Washington DC saw the decline in marriage rates slow down after 2004.

So what's really happening?

Some theories point to the economy, some argue Millennials don't feel the same societal pressure to marry as generations before them and others suggest that the younger generations simply don't need marriage anymore, instead choosing to cohabitate and raise children outside the institution of marriage.

What do you think is causing the decline in marriage rates? Tell us in the comments section below!