A good example of unintended consequences is the proposed ban of US exports of gasoline. The intuition is that will boost supply in the US market, but that intuition fails for large chunks of the country. The East Coast is heavily dependent on imports due to a lack of pipeline capacity and US flagged ships (see Jones Act). So if exports are banned then international market prices go up, and East Coast imports become more expensive. Pockets located near refiners might get cheap gas but most of the population ends up worse off.