What do you notice about the name "Smiths Falls". There is no possessive indication in the name. It originally was named Smyth's Falls in 1784. It transitioned on to Smith's Falls, and then started being written as Smiths Falls without the apostrophe. Not until 1968 did the name become official with an Act of the Ontario Legislature to officially remove the apostrophe.
There is no indication of St. Catharines having ever been a possessive phrase, even though it is thought to be named after Catharine Askin Robertson Hamilton, wife of Robert Hamilton. It seems an indication of how many variations can take place.
What about 'Farmers Market'. It has various spellings with Wikipedia's entry being named Farmers' Markets and other entries Farmers Market.
"Some farmers markets get it right, and some don't. No apostrophe is necessary in "farmers" because the phrase is what the AP Stylebook calls a descriptive phrase, not a possessive phrase. A descriptive phrase means the word "farmers" is being treated as an adjective, not as a noun."
We can see this quote comes from an Editor's Desk. Or is it the Editors' Desk? Did all the editors agree on this one.
Along the way, I found these amazing examples of irregular plurals:
If all of the women have fancy cars, you should write "the women's fancy cars."
Should you find that every deer in the woods behind your house has a blue tail, you will write "the deer's tails."
If several tornadoes strike in three different states, and each tornado destroys only a laundromat, you would write about the "phenomena's strange affinity for laundromats."
The last scenario seems to be the summary of a movie or novel. The very entertaining entry concludes with the Aberrant Apostrophe:
"Irregular plurals that still end in "s" such as knives, wives, crises and potatoes should follow Rule 1-simply place the apostrophe after the letter s. The knives' edges, wives' stories, crises' repercussions and potatoes' colors are therefore grammatically preserved."
It is train day today - this is one of Gerry's railroad scenes showing the transition from day through night and into sunrise.