[krstck]

My understanding is that transportation is actually a small factor in total food emissions. It seems that promoting "local food" without paying attention to whether that food can be optimally produced locally, might be more environmentally unfriendly than simply producing it wherever it is most efficient to produce and then transporting it.

[dredmorbius]

For rail or ship delivery especially, yes. For trucks, somewhat less so, and for air, generally not.

Ships and rail both favour crops which store well (grains) or can be shipped frozen or refrigerated. For fresh fruit and vegetables, time is critical, and you generally want to be on store shelves within at most a few days. That's where trade-offs between location, farming costs (particularly for greenhoused or hydroponic farming) vs. transport start to get factored in. There are reasons why a generation ago you simply didn't have fresh produce out of season.