The Pythagorean theorem tells you the diagonal measure (d) can be found from the equation
d² = (98 yd)^2 + (98 yd)^2
d² = 19208 yd^2
Taking the square root, we find the diagonal to be
d = √(19208 yd^2)
d ≈ 138.6 yd
The length of the diagonal of the city block is about 138.6 yards.