I know divorce is quite common in America, where it isn't that difficult to dissolve ones marital union. I have been married over 22 years, so I guess it's hard for me to understand why it can be so easy for some people.
Has divorce been around as long as the institution of marriage?
Divorce didn't become available for many years after marriage. Divorce laws vary around the world too. Most countries require a court to resolve many issues like child support, visitation, alimony, etc.
Is divorce prevalent in the United States?
Oh yes, with many reasons that one can divorce, such as infidelity, controlling spouse, financial issues, incompatibility, etc. 
What's the biggest issue that couples cite as causes for divorce?
Most cases are infidelity and financial issues. Of course, each state has different sets of rules on divorce, and some require that couples live apart for months before they will grant one.
Gosh I didn't know getting a divorce was so strict.
Some states are, some are not. The US allows people to divorce on the grounds of either fault or no fault, basically stated if you argue too much they will grant a divorce.
Ok so all you have to say is we argue and they'll grant it?