NTRAK is a model railroading society which has developed a set of standards for construction and connectivity of modular N scale model railroads. NTRAK is composed of a worldwide group of chapters that function independently or in conjunction with each other to create modular layouts which are displayed at events and gatherings.
Chapter members build modules that conform to the universal NTRAK standards, and these modules are connected—like lego™ blocks—into large layouts. The displays are used as an added attraction at an existing event, or as a draw by themselves. Layouts range from fairly small to absolutely gigantic depending on the size of a space, the number of club members & modules, and coordination with other NTRAK clubs. Adherence to the standards, allows modules from any ONE club to easily be combined with modules from any other clubs— providing the flexibility to have multi-club shows.
In 1973 a group of enthusiastic model railroaders got together at an N scale meet in Signal Hill, California, and talked about what they could do to help interest people in N scale, and to share information about N scale. The NTRAK project resulted from this meeting and the idea has spread throughout the model railroad hobby. NTRAK is a nonprofit organization run by volunteers, its purpose and objective is to encourage model railroading in N scale. There are now NTRAK clubs in most areas of the United States and Canada, there are also NTRAK clubs in Australia, England, Holland, Switzerland, Sweden, New Zealand, Japan, and many other countries.
–From ntrak.org