Why was it important to early agriculture for civilizations to be close to rivers?

Water is needed to start farms. they could also ship goods with the river. I know my answer is not well but I hoped it helped 

Early civilizations needed to be close to rivers so that they could have proper irrigation to support farms and crops.

It is the second answer

Humid continental climate is found in the interior of continents between the 30 and 60 degrees latitude, but usually above the 40 degree line.   40 degrees north of the equator means less direct sunlight and therefore less warmth.   this climate is mainly found in the northern hemisphere since there are no major landmasses in the southern hemisphere.  if you live in northern indiana, you know all about humid continental because that is the climate type you have!