The GNT is a team knockout event, broken into 4 flights (Championship, A, B & C).  The national bridge championship is held at the summer North American Bridge Championship (NABC) The event is restricted to those who have qualified in their local ACBL district.

The US Bridge Association conducted a GNT-of-4 championship from 1934 to 1937 before merger created the ACBL.  The extended, grass-roots tournament was re-established in 1973, when about 1500 teams participated.  Initial stages were contested in the 25 geographically defined ACBL districts.  Champions of 8 zones were determined in a semifinal stage, who qualified for the final stage at 1 of the NABC meets.  By 1980 there were 6032 teams in the first stage.  The zonal stage was eliminated in 1985; since then, every District champion qualifies for the final at the Summer NABC.  In 1985, the event was divided in 3 flights called A, B & C.  The Championship flight was added in 2001.  Flight eligibility is restricted by upper limits on career masterpoints.

Championship flight is open to any player.
Flight A is open only to a player who has fewer than 6000 masterpoints recorded as of the September cycle.
Flight B is open only to a player who has fewer than 2500 masterpoints recorded as of the September cycle.
Flight C is open only to a player who has fewer than 500 masterpoints who have not attained the rank of Life Master recorded as of the September cycle.