The New York Times today has an article entitled “Math Skills Suffer in U.S., Study Finds“, based on a study to be published in the Notices of the American Mathematical Society. The study found that mathematically gifted children in the U.S. were not represented as often in mathematics competitions, camps, and similar activities as in other countries, especially when restricting attention to female, native-born, or non-Asian children. Mathematically talented girls, in particular, appear to be discouraged by social and other pressures from pursuing careers in mathematics. These results are unfortunately somewhat unsurprising, but the extent to which they are present as documented in the study is rather stark. The New York Times article also interviewed several mathematically high-achieving young women (e.g. Olympiad medalists) in the U.S., who described some of these pressures in more personal terms.
It seems to me that there are some parallels between the U.S. experience and that in Australia nowadays; see for instance the remarks in the New York Times article on how sports achievement among youth is given far higher visibility than science or mathematical achievement.