NASFiC, the North American Science Fiction Convention was added to the Worldcon Constitution in the mid 1970s. It was intended to legitimatize the inevitable major convention in North America when the Worldcon was held in other parts of the world without encouraging the development of an American natcon, which would inevitably become a competitor to Worldcon.

The first NASFiC was held in Los Angeles in 1975 when the first Aussiecon was in Melbourne, Victoria, Australia. The second NASFiC (NorthAmericon) was in Louisville, Kentucky in 1979 when Brighton, England was selected for the Worldcon. The name "NASFiC" was coined by Tony Lewis.

Convention Dates Location GoHs
NASFiC (first) Labor Day weekend 1975 Los Angeles, California. Los Angeles Airport Marriott. Harlan Ellison
NorthAmericon `79 30 Aug-3 Sep 1979 Louisville, Kentucky: Galt House Hotel Frederik Pohl, George Scithers
LoneStarCon 30 Aug - 2 Sep 1985 Austin,Texas, Hyatt Regency Austin, Sheraton Crest & Palmer Auditorium Jack Vance, Richard Powers, Joanne Burger
CactusCon 3-7 Sep 1987 Phoenix, Arizona. Phoenix Hyatt Regency, Adams Hilton, Phoenix Convention Center Hal Clement, Marjii Ellers
ConDiego Labor Day weekend 1990 San Diego, California Omni Hotel, San Diego Convention & Performing Arts Center Samuel R. Delany, Ben Yalow
Dragon*Con 1995 13-16 July 1995 Atlanta, Georgia. Atlanta Hilton & Towers, Westin Peachtree Plaza Hotel & Atlanta Civic Center George Alec Effinger, Harlan Ellison, Timothy Zahn, Michael Whelan, Bjo Trimble
Conucopia 26-29 Aug 1999 Anaheim, California. Anaheim Marriott Jerry Pournelle, Ellen Datlow, Richard Lynch, Nicki Lynch
CascadiaCon 1-5 Sep 2005 Seattle, Washington Fred Saberhagen, Liz Danforth, Toni Weisskopf, Kevin Standlee
Archon 31 / Tuckercon 2-5 Aug 2007 Collinsville, Illinois. Holiday Inn Gateway Center Barbara Hambly, Darrell K. Sweet, Kevin Murphy, Bill Corbett, James Ernest, Elizabeth Covey, Barry Childs-Helton, Sally Childs-Helton, Nancy "Cleo" Hathaway, Lani Tupu, Richard Hatch
Reconstruction 5-8 Aug 2010 Raleigh, NC. Raleigh Convention Center, Raleigh Marriott City Center & Sheraton Raleigh Hotel Eric Flint, Brad Foster, Juanita Coulson
Detcon1 17-20 Jul 2014 Detroit, MI. Renaissance Center Marriott, Detroit Steven Barnes, John Picacio, Bernadette Bosky, Arthur D. Hlavaty, Kevin J. Maroney, Helen Greiner, Bill Sutton, Brenda Sutton
NorthAmeriCon '17 July 6-9, 2017 San Juan, PR. Sheraton Puerto Rico Hotel and Casino, Puerto Rico, PR. DaĆ­na Chaviano, Tobias S. Buckell, Guy Consolmagno, Javier Grillo-Marxuach, George Perez, Paula Smith
Spikecon July 4-7, 2019 Layton, UT. David Weber, Laurell K. Hamilton, Vincent Villafranca, Dragon Dronet, Susan Chang, Linda Deneroff, Bjo & John Trimble

See also Noncon (fanspeak); the major difference being that the location of the NASFiC is determined by members of the Worldcon.