Why some addresses don't geocode, and how to fix them
Published
Out of a few hundred addresses, a handful land in the wrong place or are not found. The reasons are almost always the same, and most take a few seconds to fix.
1. There is no house number
“Irlam Road, Flixton” names a road, not a building. A geocoder can only place it somewhere on that road, which may be a kilometre long. School, hospital and business lists often look like this, because everyone knows where the place is.
Fix: add the number when you have it, or the postcode. In the UK, a full postcode covers about fifteen addresses: AddressPlotter checks each British answer against the center of its postcode and, when they are more than 300 meters apart, moves the pin to the postcode center and marks it “to check”.
2. The town exists in several states
There are Springfields in more than thirty US states. An address with a street and a town but no state or ZIP code can land in the wrong one.
Fix: keep the state or ZIP column, or set the right default country above the table so at least the country is right.
3. Excel ate the leading zero
Excel stores ZIP code 02134 as the number 2134, and New Jersey’s 07001 as 7001. A geocoder that receives “7001” may not recognize it as a ZIP code.
Fix: nothing to do in AddressPlotter: in a ZIP code column, four-digit values get their zero back. In other tools, format the column as Text before typing or importing.
4. The address is not a place
PO boxes, “c/o” lines, suite numbers in the street column, or a note such as “back entrance” confuse the lookup. A PO box has no position at all: it is a counter at a post office.
Fix: move suite and floor details to a second address column (“Address 2”), and use the street address instead of a PO box when you have it.
5. The street is new, or renamed
Open map data is updated by volunteers and public sources, and new estates take time to appear. Renamed streets keep their old name in some sources for a while.
Fix: drag the pin to the right place. A point moved by hand keeps its position and is marked as placed by hand.
6. The country is missing
“10 High Street” exists in hundreds of British towns, and “123 Main St” in thousands of places. Without a country, a mixed list can send a row abroad.
Fix: add a Country column for mixed lists, or choose the default country above the table. AddressPlotter also infers the country from a state name or the shape of a postcode.
Check before you use the map
Whatever the tool, a list geocoded in bulk is only as good as its worst rows. In AddressPlotter, every doubtful point is listed under the map with its reason: “only the town was found”, “placed at the postcode center”, “not found”. Fixing them one by one takes less time than finding out later that a customer was placed in the wrong state.
Questions
What share of addresses usually needs a fix?
On clean US and Canadian lists, a few percent. On lists made of place names without house numbers, as is common in the UK, more points are only approximate and are marked to check.
Should I correct my spreadsheet or the map?
For a one-off map, drag the pin. If you will map the same list again, fix the cell too, so the address is found next time.
Why is a point marked to check when it looks right?
A point is marked when the geocoder is not sure, for example when it found the street but not the number. Many such points are right; keep them in one click.