How do political parties manage candidate selection? This paper explores how seniority systems shape career trajectories. Using extensive data from Norwegian local and national elections between 1945-2019, we identify two core norms governing party nominations: the incumbent re-nomination rule and the seniority progression principle.

Data & Methods: Comprehensive analysis of over a decade's worth of election records covering more than 30 years of Norwegian electoral history.

Key Findings: Our research reveals systematic patterns reflecting these norms, demonstrating how seemingly simple rules produce predictable career trajectories for elected officials.

Why It Matters: These findings highlight an overlooked institutional mechanism that significantly influences party cohesion and political stability in Norway.