To find the circumference of a circle, you can use the formula:
\[ C = \pi \times d \]
where \( C \) is the circumference and \( d \) is the diameter.
Given that the diameter \( d \) is 4.5 miles and using \(\pi \approx 3.14\):
\[ C = 3.14 \times 4.5 \]
Calculating this:
\[ C = 3.14 \times 4.5 = 14.13 \text{ miles} \]
So, the estimated circumference of the circle is 14.13 miles.