Semiconductor device structures including staircase structures, and related methods and electronic systems

An electronic system, comprising:

• at least one semiconductor device structure comprising:
• a stack structure including stacked tiers comprising conductive structures and insulating structures in a vertically alternating arrangement with one another, the stack structure comprising:
• at least one stadium structure comprising opposing staircase structures having steps comprising horizontal ends of the stacked tiers;
• a middle section neighboring the at least one stadium structure in a first horizontal direction and continuously extending from a top of a first of the opposing staircase structures to a top of a second of the opposing staircase structures in a second horizontal direction;
• opposing end sections integral and continuous with the stadium structure and the middle section;
• at least one opening vertically extending completely through the stack structure, the at least one opening intervening between the at least one stadium structure and the middle section in the first horizontal direction and extending from and between the opposing end sections in the second horizontal direction;
• and
• continuous conductive paths at least partially formed by the conductive structures of the stacked tiers of the stack structure, each of the stacked tiers individually exhibiting one of the conductive structures extending continuously around the at least one opening from a first of the opposing staircase structures, across each of a first of the opposing end sections, the middle section, and a second of the opposing end sections, and to a second of the opposing staircase structures.