Anomalies in the Denver street grid

In the Denver street grid, usually east-west streets are 16 blocks to the mile, and north-south streets have 8 blocks to the mile.

For example, Wadsworth Blvd is 7600 W, and Sheridan is 5200 W.  This is 24 blocks away, so you can tell that it is 1.5 miles away.  Now 1 mile east of Sheridan is Lowell Blvd, which is 3600 W.  Note however, that it is 1/2 mile from Lowell to Federal Blvd, but Federal is 3000 W.  And Federal is 1/2 mile from Zuni, but Zuni is 2400 W.  So between Zuni and Lowell, a distance of 1 mile, there are actually 24 blocks to the mile, but everywhere else it is 16 blocks to the mile.

Now a similar anomaly exists with the north-south numbering.  Usually there are east-west streets every 1/2 mile, to match the quarter-section lines and these are 4 blocks apart.  For example, from 48th Avenue to 44th Avenue is 1/2 mile.  However, 1/2 mile south of 44th Avenue is 38th Avenue (whereas you would expect it to be 40th Avenue).  And 1/2 mile south of 38th is 32nd Avenue.  And then you have 26th and 20th. 

Now a further anomaly exists.  20th Avenue is 1/2 mile north of Colfax Ave, which is 1500 N.  And 1/2 mile south of Colfax is 10th Avenue.  1/2 mile further south is 6th Avenue and then 1st Avenue.  Between 1st and Alameda (300 S) is 4 blocks. 

So we can state the rule:  In the Denver street grid, north-south streets usually have 8 blocks to the mile. 1. However, between 1st Avenue and 6th Avenue, there are 10 blocks to the mile.  2. Between 6th Avenue and 10th Avenue, there are 8 blocks to the mile.  3. Between 10th Avenue and 20th Avenue, there are 10 blocks to the mile.  4.  Between 20th Avenue and 44th Avenue, there are 12 blocks to the mile.

So these are all east-west streets, spaced 1/2 mile apart.
Exposition Ave
Alameda Avenue
1st Ave
6th Ave
10th Ave
Colfax Ave
20th Ave
26th Avenue
32nd Avenue
38th Avenue
44th Avenue
48th Avenue
52nd Avenue