Census Bureau data can help answer the question of how likely it is that a long-lasting marriage, such as the 40-year-union of Al and Tipper Gore, will come to an end.

Only a small share of long-duration marriages end in divorce each year, but the likelihood that a first marriage remains intact dwindles with each anniversary. According to a new Pew Research Center report on long-duration marriages and divorce, only about half the first marriages begun in the early 1970s lasted until their 25th anniversaries.