PolitiFact: Donald Trump and his tax returns

Donald Trump has resisted calls to release his tax returns.

In recent history, the custom certainly is for presidential nominees to do so.

But is Trump, as U.S. Sen. Tammy Baldwin (D-Wis.) charges, the only major-party nominee in 40 years not to release his returns?

PolitiFact Wisconsin finds Baldwin's claim is largely on target, but there is one exception.