The COVID-19 pandemic struck during a period of extreme polarization in American politics. Unsurprisingly, responses to it quickly became politicized despite increasingly clear findings from scientific and public health communities about the most effective approaches for limiting its spread. We ask how the politicization affected pandemic response at the state level. We document and explain several kinds of state-level actions, beginning with 2020 variations in collecting and publishing COVID-related data and early mitigation strategies. We find that state capacity explains the former and partisanship the latter. We show that divisions within the Republican Party also meaningfully affected state responses. Inter- and intraparty divisions -- rather than geography or severity of COVID -- in fact continue to influence state policy following the inauguration of President Joe Biden, the availability of vaccines, and the rise of the Delta variant. These findings document that U.S. federalism often created obstacles to effective governmental responses.