What are the closely spaced vertical members in a stairway or balcony railing called?

The correct answer identifies closely spaced vertical members in a stairway or balcony railing as balusters. Balusters are structural elements that provide support for the handrail and also serve a safety function by preventing falls through the openings in the railing. They are typically vertical and spaced evenly to create a barrier while allowing visibility through the railing system.

Newell posts, while part of the railing system, refer specifically to the larger vertical posts at the end of a railing or at landings, and they provide support for the railing as a whole. Muntins relate to window construction where they divide the panes of glass, and doweled sections typically refer to joints in woodworking, not to railing systems. Understanding the role of balusters is crucial for ensuring proper safety and adherence to building codes in environments where railings are required.