There's a news story about a woman getting busted bringing in meat from Mexico. Unless the meat is from a USDA-inspected slaughter and processing establishment, it can't be brought in. The story is noteworthy because they hid the sausages in "dirty" diapers.
The reason for the ban is that meat products can harbor diseases like classical swine fever. If pigs eat that chorizo, they could get sick and endanger the USA's herd. Haiti's herd had to be depopulated because of diseases brought in from Europe.
The rules seem anti-food and awful, until you consider that an outbreak of Classical Swine Fever or a similar disease would cost the USA's pork producers millions of dollars.