Without question, 2020 will long be remembered for the challenges faced by every organization and every individual. I am so proud of the Auto-Owners associates, and the agency personnel, for continuing to provide excellent service to the policyholders while navigating themselves, and their families, through the pandemic.
From a financial perspective, Auto-Owners enjoyed another year of profitable growth in 2020, achieving a record ninth consecutive year with an underwriting profit. The many fine independent agents that represent us favored us with more than $1.1 billion in new business premium. Total premium grew more than $300 million, or 3.9%. And that includes the premium refund made to auto policyholders during the second quarter, when vehicle usage was down considerably as we dealt with the various executive orders.
In-force policy count grew by more than 110,000, bringing our total number of policies in force to more than 5.35 million. Policyholder surplus increased to more than $13.8 billion, thanks in part to a healthy year in the stock market. We have all the capacity we need to support premium and policy growth for years to come. Auto-Owners Life Insurance Company had another excellent year as well.
Auto-Owners continues to be recognized by AM Best for our strong performance and financial strength. Our A++ (Superior) rating was reaffirmed, making it 49 consecutive years we have received their highest available rating.
Atlantic Casualty Insurance Company enjoyed another outstanding year of profitable growth. Concord General Mutual, our affiliate operating in the four northern-most New England states, also had a very successful year. This was recognized by AM Best, which upgraded Concord's financial strength rating from A to A+. Capital Insurance Group, acquired in 2019, experienced vastly improved results in 2020. Capital was also recognized by AM Best, which upgraded their financial strength rating from A- to A.
It is a privilege for me to work with so many hard-working associates who show agents every day that personal relationships matter.