The Piers Reinvestment Act aims to enhance the resilience of municipal piers by making them eligible for federal grant funding. It amends title 23, United States Code, to specifically include the strengthening, upgrading, or improving of municipal piers as an eligible activity under the Promoting Resilient Operations for Transformative, Efficient, and Cost-saving Transportation (PROTECT) program's resilience improvement grants. Furthermore, the bill expands the scope of At-Risk Coastal Infrastructure Grants to explicitly cover municipal piers, ensuring they can receive funding for protective measures. To support these expanded eligibilities, the Act increases the authorized appropriations for relevant programs from $300,000,000 to $500,000,000 , providing additional resources for these critical infrastructure improvements.