friction of distance {Ans: the increase in time and cost that usually comes with increasing distance}modes of transportation {Ans: airplanes, reduce travel time between two distant points, and as a result increase interaction}gravity model {Ans: a mathematical model that is used in a number of different types of spatial analysis, used to calculate transportation flow between two points, determine the area of influence of a city's businesses, and estimate the flow of migrants to a particular place: Equation - (Location1Population x Location2Population)/Distance^2}formal region {Ans: an area of bounded space that possesses some homogenous characteristic or uniformity}culture region boundaries {Ans: The American "Dixie" south, fuzzy borders}dot-density maps {Ans: }