United States Extemporaneous Speaking (also called Domestic Extemporaneous Speaking, and variously contracted to Domestic Extemp, U.S. Extemp, DX, or USX) is a style of competitive speaking sponsored by the National Forensic League.

Competition in USX involves the selection, preparation, and presentation of a seven-minute speech on a topic relating to United States domestic and foreign policy, domestic commerce, politics, economy, and the like. The speech is to be delivered entirely from memory. Well-received speeches generally emphasize both the oratorical and analytical aspects of the presentation. A good speaker typically employs the thirty-minute period of preparation, find relevant references in magazine and newspaper cuttings, which he or she later cites during the speech to provide backing.

In most tournaments, USX and FX competitors are gathered into an extemp prep (preparation room), where they leave their files of newspaper and magazine cuttings for the duration of the tournament. In many tournaments, the prep room is often a school library (whose magazine collection can be a minor boon to those without up-to-date files). Thirty minutes before their assigned speaking time, each competitor draws three topics (at random) from a pool, selects one of the topics, and returns the other two. The competitor then prepares a speech on the topic, and delivers it before a judge.

The judge will hear between five and seven speeches in a typical round of competition. After all speakers have finished, the judge will rank them from best to worst, and assign them each a quality score (called Quality Points, or QP).

Single-day tournaments usually feature three rounds of competition; longer tournaments typically feature three or more preliminary rounds, and a variable number of elimination rounds (although few weekend tournaments have more than two levels of elimination).