Why plane traveled on a long path while going to US where as it could adopt shorter route ?

i traveled from doha to houston, i expected the plane to go straight west over the africa and over the occen and then to houston. but i saw plane went to north and crossed over the western part of russia then turned left and crossed over the scandinavia , england green land, entered canada from north and then came straight down to US and landed at houston. it was 16 hrs and 30 mins flight. i think it could have been shorter if it traveled straight to houston. can anyone tell me reason for this long detour please.