The league began its merger process with the National Football League (NFL) in June, which took effect fully in 1970.
The season also saw the debut of the expansion Miami Dolphins, the AFL's ninth team (an odd number), requiring an idle team each week. A sixth official, the Line Judge, was added to the officiating crew; the NFL added the Line Judge the previous season.
The season ended when the Kansas City Chiefs defeated the two-time defending champion Buffalo Bills in the AFL Championship game, and were defeated by the NFL's Green Bay Packers in the first AFL-NFL World Championship Game, now known as the Super Bowl.
The AFL now had nine teams, grouped into two divisions (the new Miami team was in the Eastern Division, now with five teams), and still played a 14-game schedule. In previous seasons (with eight clubs), each played a home-and-away game against the other seven. All nine teams faced each other at least once, and each team played six others twice. Though Boston and Miami were both in the Eastern Division, they met only once, on November 27 (each team played Western Division teams Kansas City and Denver twice, while Boston also played San Diego twice and Miami played Oakland twice --- meaning that the Patriots and Dolphins each had a schedule that called for them to face three non-division opponents more often than they played a divisional opponent).
As in earlier years, the division champions met in the league championship game, with the home team rotating, this year to the Eastern champion. If there was tie in the standings, an unscheduled tiebreaker playoff would be held to determine the division winner, with the other division's winner idle.