The NMRA is the main organization in this country that is responsible for promoting the hobby of model railroading and sets the standards for measurements and specifies to manufacturers how certain products should be made so that they can be universally applied throughout the hobby. For example, all HO scale trains that are produced have to conform to certain measurements so they can be run on HO track, no matter who makes the locos, the cars or the track.
If you are excited about model railroading, even if you don't have or plan to create your own layout, you should seriously consider joining. It doesn't cost much. You can get the NMRA Magazine, formerly called Scale Rails, if you wish along with your membership. It gives you a lot of info about what's happening in the hobby along with some articles about interesting layouts, tips and techniques, and information about how to get achievement awards for good modeling.
The national organization is divided up into regional and local groups that you can join as well. This is a great way to meet up with other folks in your area who are interested in model railroading and an excellent way to learn more about the hobby. Your local group may already have a layout ready for your participation.
Whether or not you become a member of the organization, you should have a standard measurement gauge in your particular scale which you can get from them to help you in making sure the track that you lay and the equipment you run on your track conforms to the proper standards. If not, sometimes you have to do some tweaking to get everything working properly. Specific model railroading standards can be found at their website:
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