Final answer:
The exact states falling entirely within areas receiving less than 4.0 kWh/m²/day are not specified in the question, but typically these would be at higher latitudes or have more cloud coverage, with Wyoming, North Dakota, and Alabama suggested as having lower solar potential.
Step-by-step explanation:
The states that are almost entirely within areas that receive less than 4.0 kWh/m²/day of sunlight are typically found at higher latitudes and/or in regions with high amounts of cloud cover. According to the information provided, the lowest solar potential in the United States does not vary by more than a factor of two from the highest, even when comparing such diverse environments as the Mojave Desert and the Olympic Peninsula in Washington. Based on Figure 13.9, it is suggested that states like Wyoming, North Dakota, and Alabama have lower solar potential; however, specific detailed data from the map would be needed to determine the exact states with less than 4.0 kWh/m²/day of sunlight, as the question does not directly provide this information.