This study introduces a groundbreaking yearly measure of state policy liberalism in the United States, spanning 1936 to 2014.

Methodology: Dynamic latent-variable model applied to 148 policies over eight decades

* Addresses limitations of purely cross-sectional measures

* Enables detailed analysis of policy change and evolution

Key Findings:

* U.S. state policy liberalism increased steadily from the 1930s through the 1970s, then plateaued for several decades afterward.

* Most states maintained stable levels of policy liberalism relative to each other over time.

* Contrary to expectations based on multi-dimensional theoretical frameworks, surprisingly little evidence supports a multi-faceted approach to state policies.

Significance: This nuanced understanding offers new tools for examining political development, descriptive representation, and governmental accountability.