A national organization of parents who support “shared parenting” after divorce have issued a new report that rates states regarding their state law on this issue. This map shows their rankings, see the report. 
Family Law
Family Law in 50 States
Family Law in 50 States–
This website maintained by the Family Law section of the American Bar Association provides basic information on family law in each of the states. Included in the section are custody, spousal support, child support, property division, grounds for divorce and residency requirements, and third-party visitation.