In 2015, NPDA was the largest debating organization in the United States with around 200-250 participating schools in any given year.
After the announcement of the topic, the two teams have 15 minutes to prepare plus the time it takes to walk to the furthest away round in which debates will be taking place (usually rounded to 20 minutes), during which to write out their respective cases.
The standard time limits for an NPDA debate are: There are tournaments, however, at which these are modified, generally to a 7-7-7-7-5-5 format.
These are unofficial yet very popular with many judges: Debaters may not bring in printed, published evidence and consult it during the round.
It is expected that debaters will use their own pre-existing knowledge and research conducted prior to the start of the actual round to back their arguments with reasoning and empirical data.
The largest of these tournaments include the Mile High Swing held in January co-hosted in recent years[when?]