How big is the average city block in acres?

Question

How big is the average city block in acres?

Answer 1

as reference points, the standard block in Manhattan is about 264 by 900 feet (80 m × 274 m)

One acre comprises 4,840 square yards or 43,560 square feet[1]

So 5.45 acres per Manhattan city block, give or take a little change

Answer 2

In olden times, urban areas were given a measurement of one square mile.  Anything else was considered rural.

States were measured in square miles

Counties also.

cities 1 sq. mile

Each block was considered to be 1/10 of a mile in area

So 1/10 of 640 = 64 acres.

Hope this helps