Tuesday is the 40th anniversary of the U.S. Supreme Court's landmark Roe v. Wade decision, but a poll shows that many Americans don't know the significance of the case.

According to a new study released by Pew Research Center, only 62 percent of adults polled knew the decision affirmed the legality of a woman's right to abortion under the 14th Amendment to the Constitution, and only 44 percent of those polled under the age of 30 could say the case dealt with abortion.

Among the under-30 set, Pew says, 16 percent thought the case dealt with school desegregation, and 41 percent either said it dealt with another issue or had no idea what it dealt with.

In comparison, 7 percent of all adults polled incorrectly associated the decision with school desegregation, 5 percent associated it with the death penalty, and 5 percent more thought the ruling dealt with environmental protection, according to a Pew report.

One in five said they had no idea what the case dealt with.

Equal percentages of women and men were aware that the case decided abortion rights, at 62 percent each, the report said.

Political parties differed, however, with 68 percent of Republicans, 63 percent of independents and 57 percent of Democrats able to identify the historic court case, Pew said.

The telephone poll was taken Jan. 9-13 among 1,502 adults, ages 18 and older. The results were released on Jan. 16. The poll's margin of error was plus or minus 2.9 percentage points.