Over the past three decades, while most community college students aspired to a four-year degree, only about 30% successfully transferred. Despite thousands of transfer agreements, understanding which institutions, programs, disciplines, and states engage in these partnerships remains limited. Analyzing 16,452 active agreements among community colleges and four-year institutions within and out-of-state, our findings indicate that community colleges and public four-year institutions are pivotal in forming in-state transfer agreements, while out-of-state agreements are driven by private four-year colleges. In-state agreements often focus on key disciplines like business, management, and education, while out-of-state partnerships are more diverse, reflecting varied regional priorities. Though Pennsylvania, New York, Virginia, and Kentucky are the most active states in these partnerships, we observed significant spatial dependence, with neighboring states showing similar participation rates. Surprisingly, we found that statewide transfer policies decreased partnership formation. Institutional proximity and state education levels influence agreements formation, while net migration negatively impacts it. We emphasize that a better understanding of the structure of these agreements is necessary for establishing new or fostering effective partnerships that improve students' chances of a four-year degree attainment. Our takeaways/recommendations may help policymakers enhance or establish these bilateral agreements. Replication code and data are available here https://cutt.ly/4wMTRV5e. [This is the online first version of an article published in "Journal of Higher Education."]