Okla. Admin. Code § 85:10-11-15
The Code grants the power to state banks to engage in any banking activity conferred upon national banks. Federal law provides that national banks may act as agent for any fire, life, or other insurance company in any place the population of which does not exceed 5,000 inhabitants. This provision is hereby made applicable to any office of a state bank when the office is located in a place having a population of less than 5,000, even though the main office of such bank is located in a place whose population exceeds 5,000. If a bank acts as insurance agent in a place that, at the time the insurance agency was established, had a population of less than 5,000 but which has grown in size to exceed 5,000, the bank may continue to maintain the agency in such place without regard to its population. Insurance activities conducted through a financial subsidiary are not subject to the restrictions described in this section.
Okla. Admin. Code § 85:10-11-15