I am looking for some source of data on trade imbalance at a county level in the US, preferably for years 1990-2007. Does anyone know if such data can be publicly available? Or any paper that have been using data like this? Thanks in advance!
UPD: to break this down, I am looking for:
international import/export statistics by US county,
intra-state trade statistics, meaning shipments between counties within the US.