A Michigan teen who has made annual treks carrying his younger brother on his back to raise awareness about cerebral palsy on Wednesday started a 180-kilometre walk that's expected to be his last.

A 15-year-old boy strapped his 8-year-old brother to his back and walked for 91.7 kilometres (57 miles) over the weekend to raise awareness for cerebral palsy.

A Michigan teen completed a 64-kilometre, two-day trek Sunday all while carrying his seven-year-old brother on his back to raise awareness about cerebral palsy.