Fun with Streets and Sections

This may qualify under the category of “win a beer at bar” level trivia and it could be you need to be quite the dork to care, but here’s something interesting that I learned this week in broker licensing classes.

The greater Phoenix area’s are built on a grid system. This, at the risk of understatement, is the greatest invention in the history of mankind, though my opinion could be colored by my own adventures attempting to get around non-grid areas like Minneapolis in the past. Numbered streets at to the east of Central Avenue, numbered avenues to the west and named roads run east-west across town. Nearly all of the major roads are one mile apart – this is because they follow the Gila & Salt River Baseline and Meridian survey. Without going into too much detail, inside the survey are things called townships and sections, and the sections are one mile square. Thus the one-mile distance between streets.

Still with me? Good deal.

I think most of you will agree that the earth is in fact not flat. So, because of the curvature of the earth, there are adjustments made every 24 miles give or take, where the north-south roads (also known as meridians), jog just under two hundred feet to the west. The example used in class was the area in Mesa-Tempe south of Baseline road which, in practice, really is somewhere between south of US 60 and south of Baseline. Having grown up in the area, I knew the roads all bent but didn’t have the slightest idea why.

Driving home last night, I noticed the first time a similar jog on 51st Avenue south of Bell. Checking the map, there’s this …

There’s a problem, though, with my theory as it pertains to the west side; the adjustments are supposed to come every 24 miles and this area’s only about 18 to 19 miles away from the adjustment near Baseline road. At the same time, there is no grid much further north of the area. Above Union Hills and especially north of Deer Valley the roads are a hodgepodge thanks to multiple hills and the less-dense population.

But, honestly, if you’re drinking in Glendale or northwest Phoenix, you’ll still probably win a beer.

Jonathan Dalton

Jonathan Dalton is a 40-plus-year resident of the Valley and has been helping folks buy and sell homes since 2004. He can be reached at 602-502-9693 or info at


  • John Vescova 5 months ago

    Jonathan, I wanted to add a bit for you (i was looking for the opportunity for a free beer) as there are some holes in your info. I understand you did not want to go into too much detail. For your readers and you, I will expend slightly on your info. There is another and as equally important item in the measurement called ranges. These in unison with Townships create that grid. The inner grid is created by sections and section lines. The 36 sections are roughly each 640 acres (1 mile by 1 mile). A legal land description of a section includes the State, Principal Meridian name, Township and Range designations with directions, and the section number: Gila & Salt River Base Meridian, T3N, R2E, Sec7 is needed to describe an area where you live. Sorry I may have given away your nearest 640 acres.
    Anyway, they are supposed to all be 640 acres, and as you mentioned the curvature over the Earth creates a problem. The corrected areas are all made within the northern and western most 40 acre lots called government lots or GLO Lots. There is more detail on this too. Additionally, there are corrections at every 24 miles north and south along the parallel to the baseline (Baseline Rd)and 24 miles east and west of the meridians lines (107Ave). Also, this same mapping system is applied to Minneapolis, which has it baseline (I think) in Wisconsin, but many street and growth started there prior to the our government mapping all that land many years ago. There are 37 base and meridians throughout most of the US. except for I think 19/20 states.
    This is from my experience etc from my life in the civil engineering community I thought I would share.

  • Jonathan 5 months ago

    Good info … yeah, there were limits to how deep I wanted to go on it and happy to defer to you. Free beer. TBD

Comments are closed.