Which regulation governs the Unit Status Report (USR)?

The correct answer is that the regulation governing the Unit Status Report (USR) is indeed AR 220-1 and DRRS-A PPM-1. This combination of regulations specifically outlines the policy and procedures for determining and reporting the status of Army units. AR 220-1 provides the overall structure, guidance, and framework for the unit status reporting process, while the DRRS-A PPM-1 outlines additional pertinent details related to the Defense Readiness Reporting System-Army (DRRS-A), which is pertinent for capturing and reporting readiness data.

Understanding the context of these regulations is key as they ensure that all levels of command have accurate information about unit readiness to assist in resource allocation and operational planning.