January 2025, for the first time in the postwar history of Germany's national parliament, a mainstream political party (the Christian Democratic Union) relied on the support of the Alternative for Germany (AfD) to pass a motion. This prompted intense public debate as many Germans worried that this cooperation was a harbinger of possibly still more cooperation to come. Against this backdrop, our study examines the state of the so-called "firewall" - the self-commitment of established parties to not cooperate with the AfD - in Germany at the district level. To do so, we analyzed more than 11,000 meetings of councils at the district level across all federal states from mid-2019 to mid-2024. Our analysis shows that in this period no cooperation with the AfD took place in approximately 81.2% of cases where cooperation was possible. While regional differences across Germany can be observed, on average there was no significant difference in levels of cooperation between eastern and western German districts. Even in western German districts, the firewall has not strictly been upheld everywhere. However, larger differences do become apparent when comparing rural and urban districts. Eastern German rural districts, in particular, are at the forefront of cooperation with the AfD, whereas in western German districts, there is no significant urban-rural divide. From a party-political perspective, smaller parties are the most frequent collaborators with the AfD, followed by the FDP and CDU. While the firewall is beginning to crack, as of fall 2024, it had not yet completely collapsed at the district level.