From the book: The United States Air Force in Southeast Asia, 1961-1973: An Illustrated Account.
"To reduce mission interference between land-based Air Force and Navy carrier aircraft operating over North Vietnam, in December 1965 -- after consulting with Air Force and Navy officials -- Admiral Sharp divided the bombing area into six major "route packages." Generally, the longer-range USAF fighters attacked the inland route package targets; the shorter-range Navy aircraft concentrated on those near the coast. In April 1966, General Westmoreland assumed responsibility for armed reconnaissance and intelligence analysis of the "extended battlefield" area of Route Package 1 above the DMZ as it affected allied operations in South Vietnam. CINCPAC continued to control air operations in the other route packages."
Air Force History and Museums Program, Washington, DC.