Completely forget about rivers and compass directions. The two things are not related. Instead, think about rivers and mountains. Rivers always flow away from the mountain peaks. If they run from one range of mountains toward another, they'll curve away from the second range, much like the rivers in the Midwest United States do. They form downhill from the Rocky Mountains and flow eastward until the land starts to rise headed for the Appalachians, then they curl south toward the Caribbean Sea.

Rivers that start in the northern part of the Black Hills, though, such as North Dakota's Red River, will flow northward into Canada, eventually reaching the Hudson Bay.

On Earth, rivers that flow northward are relatively rare, but they do exist. Most are relatively short, but aside from the 4000 mile long Nile, there are three in Russia over 2000 miles (the Lena, Ob, and Yenissey).

Possibly the most well known river other than the Nile that flows to the north is the Niagara River, though it is only 40 miles long.