Near the end of some Wikipedia articles, below references and above categories, you may notice some boxes with links to similar articles. These are called navigation boxes, or navboxes. They are your on-site GPS, a way to navigate and find articles with a common theme or topic.
While similar to categories, these are curated to keep them focused and useful, and any article listed within a navbox will feature the same navbox in turn. Their formatting also makes crystal clear which are major topics, sub-topics, and how they relate.
Not all articles contain navboxes. And some contain several. While reading about the Michigan primary, you saw three collapsible tables for the 2016 election by state, candidates by party and presidential primaries and caucuses.