The Vikings renovated an offensive line that sputtered through last season, seeking better balance with their potentially dominant defense.
The Lions brought in new blockers, too, aiming to revive a dormant ground game and give franchise cornerstone Matthew Stafford more support.
The Bears traded up for quarterback Mitchell Trubisky with the second pick in the draft, solidifying a long-range strategy.
Ambitions and hopes are high, of course, at this time of the year. The long-term NFL optimism around the Great Lakes states inevitably took a bit of a hit on Aug. 3, though, when Aaron Rodgers made clear his disinterest in retirement or departure from the Green Bay Packers anytime soon .
The NFC North competition sure can't count on a reprieve from these twice-annual matchups against one of the league's best .
Asked if he could envision playing as long as Tom Brady has with the New England Patriots, on the day one of his few peers in the league turned 40, Rodgers left no doubt.
"I do think it's realistic," said Rodgers, who will be 34 on Dec. 2. "I hope it's in this locker room, though. That would mean it's been at a high level."
Engineering an eighth straight playoff appearance for the Packers last season, including a fifth division title in that span, Rodgers produced a vintage run of dominance following a 4-6 start by the team that was marked by some rather ordinary performances by his elite standard.
He threw 21 touchdown passes, with one interception, to lead the Packers to eight straight victories until falling to the Atlanta Falcons in the NFC championship game.
"I still feel pretty young," Rodgers said after that game. "I think I have a number of years left in me."
Here are some of the headlines around the division as September approaches:
STACKING THE SECONDARY
Only one team in the NFL allowed more passing yards last season than the Packers. Only two teams gave up more touchdowns through the air. The priority for 2017, thus, was obvious. Cornerback Kevin King and safety Josh Jones were their first two draft picks, and cornerback Davon House returned as a free agent following a two-year stay in Jacksonville.
The goal was to build a bigger and stronger secondary, with hands-on, hard-press coverage at the line of scrimmage considered these days a defense's best weapon for disruption of an opponent's passing attack.
With starting cornerbacks Damarious Randall and Quinten Rollins each entering their third seasons and fourth-year safety Ha Ha Clinton-Dix coming off his first Pro Bowl appearance, there's plenty of potential for this group to improve.
BRADFORD PROTECTION PROGRAM
After surpassing the Packers in 2015 to finish 11-5 for the division title and starting last season 5-0, the Vikings careened off-track because of some uncharacteristic lapses by the defense at critical moments, struggles by since-cut kicker Blair Walsh and a litany of injuries along the offensive line.
Even when fully healthy, there were questions about the protection, but Sam Bradford too often had to settle for a menu of quick, short throws to evade the pass rush. The running game was no help. Given time, Bradford proved his accuracy .
But he took a career-most 37 sacks, a trend that can't continue if the Vikings are going to keep him healthy, let alone return to the playoffs. They signed two new tackles, Riley Reiff (Detroit) and Mike Remmers (Carolina), to try to bolster the front.
The Lions accumulated the third-fewest rushing yards in the league in 2016 after finishing last the previous season. Still counting on some combination of Ameer Abdullah, Theo Riddick, Dwayne Washington and Zach Zenner to better supplement Stafford in the offense , the Lions also attempted an offensive line upgrade with right guard T.J. Lang arriving from Green Bay and right tackle Rick Wagner signed away from Baltimore to replace Reiff.
Greg Robinson will be the new starter at left tackle, where cornerstone Taylor Decker has been absent since shoulder surgery in June that could keep him out for a significant portion of the season.
Having engineered an NFL record with eight wins for the Lions in 2016 following fourth-quarter deficits, Stafford now has the richest contract ($135 million maximum value) in league history. The ninth-year quarterback will need a lot more help for the Lions to match last season's winning record.
REBUILDING THE BEARS
Trubisky will wait behind Mike Glennon for now, with the Bears seeking to begin a long climb from the deep hole they plummeted into during a 3-13 finish in 2016. There are pieces in place to accelerate the process, starting with running back Jordan Howard and his 1,300-yard rookie year.
The defense was so ravaged by injuries last season it was difficult to tell, but there are enough standouts in the front seven to make for a miserable afternoon for more than one unprepared opponent. Linebackers Danny Trevathan and Leonard Floyd and defensive linemen Eddie Goldman and Akiem Hicks will lead the way.