I read something lately (maybe on this forum) about 1928 Catholic presidential candidate Al Smith not knowing the name of the pope reigning at the time. The point that was being made is that popes in the past were not world famous figures, and even many Catholics didn't know their names. This seems ludicrous. Anyone know where I read this?

It looks like an element of some sort of stump speech where Al Smith is try to prove he would not be subservient to the Pope. This was an era of radio, telegraph and telephones. It was a fairly well connected world. Not knowing the Pope might seem credible in 1828 or earlier where a great number priests and bishops appointed by royal patronage meant that it often fell to the lazy, semi literate, atheistic (Louis XVI's Archbishop of Paris and Finance Minister) to teach the Faith. Al Smith was a senior politician in a well connected world, and committed to his Faith. Papal communication, most obviously encyclicals were published in English and dissected in pamphlets by groups such the Catholic Truth Society. That 1920s was an era of notable male religiosity too.