Focus on a volunteer experience that will be significant to you and enable you to take on responsibility other than just to show up for 3 hours a week. Also, where ECs are weak, colleges like to see part-time employment. Your dedication to Piano and Swimming will be viewed positively. If you partake in these activities with others (play piano in an ensemble or swim on a team), then emphasize that, as colleges want to see that you desire to be part of a larger community.
As for Minnesota-based schools, Macalester College has a great Economics curriculum and is located in St. Paul. Would it be possible to commute? They award merit and need-based aid, but there is no set formula.
Some state universities that award significant merit aid to high stats out of state students: Alabama (100% tuition); Ohio State (up to 50% tuition); North Carolina State (Park Scholarship - 100% of all costs, but very competitive); Maryland (up to 30% tuition).
Some private schools that award significant merit aid to high stats students: Case Western (50%); Tulane (50% to 75%), with some full scholarships on a very competitive basis; Bard (Levy Scholarship for Economics, 100% tuition, very competitive).
It is very good that you are getting an early start. Most of these merit programs favor (or are limited) to students who apply early action or by an earlier deadline than regular admission.
The list above is by no means exhaustive, but just based on our family’s experience. I hope you find it useful as you put your list together.