When building a home, contractors begin digging a hole in the ground a little larger thhnan the space your basement and foundation will need. Then they build the foundation inside this space and pour the concrete floor. Once they finish the foundation, they use some of the excavated soil to fill in the gap around the outer edge of your foundation. This "backfill" soil will be loose and fluffed from the excavation. Meanwhile, the untouched "virgin soil" may have been settling for hundreds, even thousands of years.
What does this mean for you? The backfilled soil surrounding your foundation will always be looser and more absorbent of water than the dense, hard-packed soil around it. This forms a sort of "clay bowl" around your house, one that creates an artificial water table around your home. Water collects the most right around your foundation, exactly where you don't want it to be.