Political parties in the U.S. are composed of networks of interest groups, according to the extended party network theory. Scholars have focused on national extended party networks. We use the case of education interest groups to explore how policy environments shape party networks on the state level. Using 145,000 campaign contributions from 2000 to 2017, we show that the alignment of education interest groups has changed over time. In 2000, teachers unions were the dominant group and aligned with Democrats. Meanwhile, Republicans lacked support from any education group. This pattern was relatively consistent across states. Over time, coalitions diverged, with some state networks polarizing, meaning unions increasingly aligned with Democrats and reform groups with Republicans, while others did not experience such polarization. We find that labor law restrictions and private school choice programs were related to these trends, suggesting that state-level policies shape the contours of state party networks.