At this time four years ago, Barack Obama's campaign had about 30 field offices up and running in Iowa, compared to six offices for Republican presidential candidate John McCain.
Obama's campaign has had eight Iowa field offices open this summer and is rolling out another 26 offices around Iowa this weekend. So far, Mitt Romney's campaign has ten Iowa field offices, in addition to the unified Republican headquarters in Urbandale.
After the jump, I compare the field office locations for each presidential campaign, grouped by Iowa Congressional district. Where relevant, I've also noted competitive Iowa House and Senate districts near the Obama and Romney field offices, although I doubt either presidential campaign will do much for down-ticket Democratic or Republican candidates.