Congressional Quarterly notes, in the form of a trivia question, that Iowa's 4th Distrist has the fifth highest percentage of white voters among the districts President Obama won last fall:
The pro-Obama district with the highest percentage of white population is Maine’s 2nd, where 96.7 percent of the residents are non-Hispanic whites. This mostly rural district takes up most of the state’s land area and is represented in the U.S. House by Democrat Michael H. Michaud .
Obama also carried Vermont, a state with one at-large House district held by Democrat Peter Welch , where 96.2 percent of the residents are non-Hispanic whites; New Hampshire’s 1st (95.1 percent), represented by Democrat Carol Shea-Porter ; and Iowa’s 4th (94.7 percent), held by Republican Tom Latham.
One of these things is not like the others: four Democratic-held New England districts and Tom Latham.