Membership renewal is from January to March 1st. You need not live in Thornton to become a member so please encourage your friends to join. Choose a one-time life membership to avoid yearly renewal, or an individual membership.  Please visit the How to become a Member page to fill out a membership form. Or you can visit the museum on the first or third Saturdays from now until May. Individual Membership: $15. Lifetime Membership: $150.