There’s an interesting documentary being put together now, called Less Car, More Go, a crowd-sourced look at use of bikes for cargo transportation and car replacement.  One little snippet of it has been released thus far, giving some insight into the history of longtail cargo bikes–at least in their Xtracycle form.

Birth of an American Cargo Bike from Liz Canning on Vimeo.

If you haven’t seen it, it’s worth a look.