For one electronics maker, over half of their components come from China. They're on the tariff list.
Some firms are adding production lines in other Asian countries.
High demand and short supply mean some labels are all but unavailable in stores.
Wal-Mart wants suppliers to list exactly which factories they work with. The retail giant says it will cut ties with anyone who subcontracts work without permission.
Exports from big states like Texas, California and Michigan have soared since the 1990s when the North American Free Trade Agreement opened U.S. markets to Mexico. But not every state has been as savvy promoting cross-border trade.
BBC World Service
A key component for building cars both here and around the world has has been nearly decimated by an explosion a couple of weeks ago in Germany.
Today the Bank of Japan is holding a meeting to talk about monetary policy for the third largest economy in the world, one year after the earthquake tsunami and nuclear disaster there.