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Basic spatial and location concepts in economic geography:
1. Location (situation):
Location is the geographical situation of a particular phenomenon; its point or position in space. It is usually measured by distance and direction.  Relative location is measured by the cost, both in money and time, required to overcome the distance. These costs are referred to as the friction of distance.
2. Economic Rent:
The difference between the total revenue received from the sale of a commodity and the total costs of production and transport.  As used in the agriculture geography, economic rent is the surplus return or profit resulting from using land for one type of production rather than another.  The revenue received is determined by the market price for that commodity and this, in turn, is response to the supply and demand situation. Production is assumed to be the fixed, but the transportation costs increase with distance from market. The greater the transportation costs, the smaller the difference between revenue and total costs, and therefore the smaller the economic rent. This type of economic rent is also called "location rent".
3. Spatial integration:
Spatial integration is the linkage between locations through transportation, communication.  The flow of goods, people, and information are collectively known as spatial interaction.
4. Spatial structure:
The arrangement and organization of phenomena on the earth's surface resulting from the operation of physical and/or human process. It is the internal organization of a distribution---the location of the elements of distribution with respect to each other.  Spatial structures limit, channel, or control spatial processes.
5. Spatial interaction (distance decay effect):
Spatial interaction is the interdependence of areas, the movement of people, capital goods, information, ideas, etc. between places. Distance decay is based on the general principle that whilst 'everything is related to everything else, near things are more related than distant things; In other words, the amount of interaction between two places or objects decreases as the distance between them increases.
6. Agglomeration and Accessibility:
In the economic landscape, agglomeration refers to the clustering of activities and people at nodal points (e.g. towns and cities). This clustering is prompted by centripetal forces in spatial organization and by the need to achieve agglomeration economies. Centripetal forces are used in the context of urban growth to identify those forces that encourage the centralization of businesses and services, particularly in the central business district.
7. Agglomeration Economies:
The potential savings to be made by a firm as a result of locating within an agglomeration, these savings occur 1) because the firm is able to share with others in the agglomeration, rather than bear alone, the full costs of such items as public utilities and specialist services; 2) because agglomeration means that distances, and therefore transport costs, are minimized by those firms between which there is some form of linkage; AND 3) because of communications economies. The scale of potential savings may be thought of as being directly proportional to the scale of agglomeration. Extensions of the concept of distance. For example, a shopping center reduces the distance consumers must travel to purchase goods by clustering (agglomeration) many stores at one point. A city itself is a clustering strategy, reducing aggregate distance among residential, business, and recreational functions, making them more accessible to the population.
8. Cause of the Urban Spread:
Suburbanization of household is closely associated with intraurban transportation improvements.  With each revolution in transportation, travel costs were lowered, and families become less willing to pay high rents for central locations. since 1945, the desire for single-family home in the suburbs has resulted in rapid suburban expansion.  Factors that have reinforced this trend are 1) low mortgage interest rate, 2) load guarantees provided under federal housing and veterans' benefit programs, 3) property tax reductions for owner occupied homes, 4) cheap transportation, 5) massive highway subsidies, 6) cheap land.