This chapter applies the ? model to the United States of America. By assuming that the US is a ‘world-system,' we can measure the economic efficiency of each state (and the District of Columbia). The model predicts an output floor based on the inputs of land and people as per-unit energy-equivalents. This expected output is then compared to the actual Gross State Product (GSP) as a per-unit energy-equivalent. States that are economically efficient register a positive residual, and hence a positive ? score. However, given potential measurement inaccuracies, states with low negative scores are also added to this efficient tier.
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Figure 1 shows the ‘efficient’ US states in dark green. These states are considered ‘sinks’ in that they are able to absorb and accumulate capital. The rest (the ‘sources’) are shown in a (decreasing efficiency) gradient from light green to yellow, and finally dark red.
Figure 1. A 2015 efficiency map of the US states; highest efficiency scores are in dark green.
Table 1 provides the actual scores for the four tiers in Figure 1. A detailed analysis of the 50 states and the District of Columbia can be found in the appendix to this chapter.
The highest-ranking states are divided into two tiers, each having the same number of states (with the District of Columbia going to the first tier). According to the model, in 2015, there were only seven states with positive scores. However, there are another six states that received scores very close to zero. States with ‘equilibrium’ band scores 
were also added to this tier. The total number of states in this tier is 20. Note how most of these states are on the East Coast. The rest (California and Washington) are on the West Coast. Most of these states are also the oldest. Twelve of the thirteen original colonies are in the first tier: Connecticut, Massachusetts, New Jersey, Maryland, New York, Rhode Island, Virginia, Pennsylvania, Delaware, New Hampshire, North Carolina and Georgia are original US colonies. Only South Carolina is in the second tier. The rest of the first tier is composed of states that are geographically close to these original states. The three exceptions are West Virginia, Kentucky, and South Carolina, which are juxtaposed to the original states but do not make it to the first-tier.
Table 1. A breakdown of the four efficiency tiers in Figure 1
The next tier, shown in light green in Figure 1, has 20 states. These second-tier states are all inefficient, exhibiting scores within the range 
. They spread further west—all the way to the Pacific Ocean (Oregon), but with an inland gap constituting third-tier states (shown in yellow in Figure 1). Hawaii, California, and Washington are in tier one. West Virginia, Kentucky, and South Carolina are all in this second tier. The best-performing state in this tier is Texas. The worst-performing is Maine.
Third tier states have efficiency scores of negative two and below. These states, shown in yellow in Figure 1, are all inland―none have access to coasts. In contrast, all first-tier states (except Tennessee) have access either to the Atlantic Ocean, the Pacific Ocean, or the Laurentian Great Lakes. This tier exhibits a wider inefficiency band, from scores of negative two to negative five 
.
The last tier, shown in dark red in Figure 1, has only one state, Alaska, which registers an efficiency score of 
, compared to the lowest score of 
in the second tier, which belongs to Montana.