O Gauge Railroading is a print and digital magazine for O Gauge model train hobbyists. They are always looking for layout articles and how-to feature articles. High quality photos accompanying the articles are a plus. The layout features should be 1,200 to 1,500 words long. They pay $400 for layout features and $200 for how-to features. For details, visit this page.
Model Railroader is a monthly magazine for model railroad enthusiasts. Editors look for material on different aspects of model railroading and on prototype (real) railroading as a subject for modeling.Articles must be short: according to guidelines, most articles are 1/3 text and 2/3 photos/illustrations. Payment is $75- $100 per printed page. To learn more, read their contributor guidelines.
Classic Toy Trains publishes articles on all aspects of "S, O, and Standard gauge toy trains." Topics covered include various historical toy trains or accessories, interesting layouts, and the history or collectibility of certain models. They previously indicated payment of $75 per page. To learn more read, read their contributor guidelines.
Trains -- They want photographs, news stories and feature articles covering railroading's past and present, including first-person recollections. They do not buy travel stories, poetry, or fiction. Each issue contains 80-100 photos and 27,000 words. Pay is $15-300 for photos, and begins at $0.10/word for text. Query first. Details here.
Model Railroad Hobbyist is a free magazine for people interested in Model Railroads. They typically pay around $230 per article of 3,000 words, plus photos. These are rather bad rates, as is pointed out in the discussion
below their submission
guidelines.