Over the last few decades, divorce rates have actually fallen. According to a USA Today article, divorce rates peaked in 1981 at a rate of 5.3 divorces per 1,000 people. When the article was published in 2007, that rate had fallen to 3.6 divorces per 1,000 people. Provisional CDC data through August 2009 show an even lower rate: 3.4. There is debate over the oft-cited statistic that half of today's marriages will end in divorce; "experts" cited in the above-linked USA Today article indicate that the divorce rate measured by that statistic is somewhere between 40 and 45%.
It is generally agreed that divorce rates are lower among more highly-educated and affluent couples, as well as among couples who delay marriage (USA Today, Time Magazine). Similarly, a research paper out of Harvard University entitled The Spread of Single-Parent Families in the United States since 1960 reports that "whereas divorce leveled off around 1980, the fraction of children born out of wedlock continued to rise until the mid-1990s. Since then the rate of increase has slowed dramatically," though it is still increasing. The paper also indicates, though, that much of this rise may be due to unmarried but cohabitating couples, although research is mixed regarding whether those couples will eventually marry or split up.