Neil_OZ,

Chicago is a very easy city to navigate. it's exactly as you thought.

Chicago was built on a grid system with a "major" street every half mile - equal to four blocks. The starting point is at the intersection of State and Madison in the heart of the Loop. State Street runs north/south. All of the other north/south streets are numbered as so many blocks east or west of State, with the addresses increasing by 100 for each block (except downtown, where streets do not always correspond to a full block).

For example, Ashland Avenue runs north/south and is 16 blocks west of State and so its "address" is 1600 West. Since there are 8 blocks to a mile, we can also determine that Ashland is 2 miles west of State. Similarly all east/west streets are numbered as north or south of Madison, which runs east/west. The street that runs parallel to Madison eight blocks to the north (Chicago Avenue) is referred to as 800 North, and is one mile north of Madison. Using this system you can always figure out how far and in what direction you have strayed from downtown, and by knowing a cross street's address you can find any building in the city. A building with an address of 800 North Ashland Ave. will be 8 blocks north of Madison on Ashland which is 16 blocks west of State Street, at the intersection of Chicago Ave. and Ashland Ave. A building with an address of 1601 West Chicago Ave. will be on another corner of the same intersection

AAFF, the first digit of my house number is also 1, and I can see now that my description was unclear. What I meant was the address of the first house on the street is not usually going to be 1 Elm Street, then the next house would not be 2 Elm Street, etc. My friends from the UK have an address like this, with single digit house #'s. That's why they thought that because my house # is in the 14000 range, it must be a very long street with 14000 houses on it. In fact, my street only has 20 homes, and the first house on the street is 14000, not 1.

Sorry for the confusion, does this make sense?

Thanks, AAFF - pity we're not going as far east as Chicago. Ironically my city, Canberra, was originally designed by a Chicagoan, Walter Burley Griffin (not to mention his wife, Marion Mahoney Griffin), and there's hardly a straight street in town - our circles are the bane of interstate visitors.

Here's what I know about the Zip Code system. (For background, my father retired as a rural carrier from the USPS and I also worked closely with a mailroom in a former life >wink<).

Zip codes are numbered across the country generally from east to west. Your low number zip codes are in the eastern half of the country, and they go up as you go west. The lowest numbers are in New England -- those starting with 0. The highest Zip codes are for towns in Alaska.

A town can have more than one zip code, depending on its size. Small towns use the same zip code for all city and rural routes as well as post office boxes. Larger cities may have a different zip code for post office boxes and city routes (ie., home/office delivery). In very large cities such as NYC, there may be one zip code serving only one large building.

Each state is divided into postal regions, but I forget the USPS term for them. For example, here where I live in East Tennessee, our zip codes all begin with 376. The main Post Office (which is in my city) is 37601. Other zip codes in my city range from 37602 through 37615.

Zip codes in the other towns of the 376 area are assigned alphabetically. Both 37617 and 37619 are towns that start with B. 37643 is an E town. 37682 is a town beginning with M. 37692 is U. 37694 is W. All mail delivered to or sent from a 376 zip code goes through our 37601 mail facility for sorting.

Towns a little west of here have 377 zip codes, and then you get to the Knoxville area with 379 zip codes. Nashville zip codes are 372. Memphis zip codes are 375. (Notice I earlier said zip codes were *generally* east-to-west -- they are a little mixed up in Tennessee.)

Zip+4 codes were implemented to help pinpoint mail delivery. Post office boxes usually have a +4 that corresponds to the box number. On city routes, I believe a different +4 is typically assigned to the two sides of each block. You'll have some variations of course. By using +4 zip codes, machinery can better sort the mail before it gets to each carrier, who still ultimately hand sorts for delivery on his or her route.

That's how zip codes work to the best of my knowledge.

For reference, I found this website -- http://tinyurl.com/z3z34 -- listing all zip codes alphabetically and numerically by state.

PS -- thanks for helping cure my insomnia. LOL.

Peter, some entities that receive a lot of mail have their own zip codes within a zip code area...maybe the Chancellor fits this description. I know that when I was at US Coast Guard Headquarters in Washington, DC, we had a unique zip code that still fell numerically into the area's zip code.

All you ever wanted to know about ZIP codes but were afraid to ask! ! Thanks to all for sharing your considerable knowledge. I shall bear it in mind when we visit CA next month.

Cheers
Peter
UK

My ZIP is 37700 and refers to Col. Centro here in San Miguel de Allende Gto., Mexico.
Other Colonias have diff ZIPs.
Get no mail here, but it defines our 'hood.
M

Why aren't the houses numbered sequentially, as in 2, 4, 6, etc? The accepted system in the US is to measure the distance in feet from the central point (the main street). In other words, the size of the house lot determines the numbering. As you move away from the central point, the odd-numbered houses should be on your left and the even on your right. Modern subdivisions with cul-de-sacs and looping streets make it difficult to follow the old rules, so sometimes it's really hard to figure out the numbering. I was once a city planner and I was always thrown by doorway numbering problems. Today I live in a private gated community that is unincorporated (out in the country) and we have a very logical system: 2,4,6 on one side and 1,3,5 on the other. The only logical thing about the prevailing US system is the the first number(s) denote the number of blocks from the central point (so 2024 is 20 blocks from the CP). A house at 13531 would be 135 blocks from the CP. The last two numbers are the house number.