Attending the International Plowing Match is one of the sacred cows of Ontario politics, with members of all parties repeating this ritual each September.

The politicians flock to a field in a rural part of the province, wearing jeans and boots. They talk of how agriculture is the lifeblood of Ontario. They shake the calloused hands of farmers. Then each party leader tries to plow the straightest furrow while driving a tractor painted in his or her party colours.

The ritual is so ingrained in provincial politics that the Legislature adjourns for two days to allow MPPs to attend.

The annual event happens again Tuesday, this time in Walton (about 40 minutes northwest of Stratford). Premier Kathleen Wynne will be there on her red tractor, PC leader Patrick Brown on a blue tractor, NDP leader Andrea Horwath on an orange tractor and Green Party leader Mike Schreiner on — you guessed it — a green tractor.

From a purely politically strategic standpoint, they really needn't bother going.

Ontario PC Leader Patrick Brown takes part in the VIP plowing competition during the 2015 International Plowing Match in Finch. (Sean Kilpatrick/The Canadian Press)

The 2018 election will be the first one contested under a new distribution of ridings that more accurately reflects where Ontario's population lives: in cities. There will be 124 seats up for grabs, and even by the most generous definition, farming is a major industry in barely 25 of those ridings.

Do the math, and you'll see that winning rural Ontario is simply not enough to send a party on the path to electoral victory. Just ask the Progressive Conservatives: they've pretty much had a stranglehold on rural seats and haven't won an election since 1999.

In 2014, Wynne's Liberals won a majority despite taking just three seats that you could argue are in farm country: Glengarry-Prescott-Russell, Northumberland-Quinte West and Brant.

Next year, the Liberals could lose all three and still end up winning. That's because there will 15 new seats created in urban areas. Those new seats, as well as the 905, will be where the election is won or lost.

Ontario NDP Leader Andrea Horwath takes part in a VIP plowing competition during the 2016 International Plowing Match in Harriston. (Hannah Yoon/The Canadian Press)

Back in 2011, anger over wind turbines meant that Dalton McGuinty's Liberals were pretty much wiped off the electoral map in rural Ontario. They still won. (That year, the Plowing Match happened in the middle of the election campaign, and all the parties diverted their campaign buses to one of the easternmost points in this province to attend.)

As Ontario becomes more urban, the influence of rural voters is diminishing. It's the way things go in a system of representation by population when the population lives in cities.

None of this is to say that agriculture is unimportant. If you had something to eat today, thank a farmer. Nor is this a justification for politicians to ignore the legitimate concerns of rural Ontario. Nor is this to suggest that it's good to have a party in power that has no presence in farm country.

Former premier Dalton McGuinty at the International Plowing Match during the 2011 election campaign.

Also, the International Plowing Match is loads of fun. The event is far more than a tractor contest, it's a multi-day trade show and agricultural expo. It is also a good barometer of public opinion in rural Ontario. Last September, amid sky-high electricity prices, Wynne was roundly booed. It will be worth watching how she's treated this year, with a minimum wage increase on the horizon.

Ontario politicians will no doubt keep attending the event, even if all they're doing is making an empty, ritualistic nod to agriculture.

But you can guarantee that the political strategists in all the parties have done the math too and will spend very little of their energy and resources on trying to win rural seats in 2018.