Navy Columbia (SSBN-826) Class Ballistic Missile Submarine Program: Background and Issues for Congress [Updated February 19, 2021] [open pdf - 2MB]
From the Summary: "The Navy's Columbia (SSBN-826) class ballistic missile submarine (SSBN) program is a program to design and build a class of 12 new SSBNs to replace the Navy's current force of 14 aging Ohio-class SSBNs. The Navy has identified the Columbia-class program as the Navy's top priority program. The Navy procured the first Columbia-class boat in FY2021 and wants to procure the second boat in the class in FY2024."
CRS Report for Congress, R41129
Congressional Research Service: https://crsreports.congress.gov/