Four years is a long time to work without a contract. Unless you’re a teacher in Pennsylvania. Then it’s not very surprising at all.

Take South Butler School District — where last week unionized teachers said they would strike starting March 15, amid contract negotiations that have run on for nearly four years now.

The spectre of a teachers strike is unsettling. But the thing is, the situation on display at South Butler isn’t all that uncommon. Teachers unions and school districts routinely push contract negotiations through years of proposals and counterproposals — and that’s despite most discussions beginning well in advance of the expiration date of the previous contract.

Currently the longest-standing contract dispute in Butler County is at South Butler, where teachers have been working without a collective bargaining agreement since June 30, 2014.

On balance, there’s nothing wrong with lengthy negotiation periods. They can help the parties refine their proposals, figure out what aspects of a deal are most important to their members and strike a balance between taxpayer and union interests.

But as a practical matter things aren’t so simple. Lengthy contract negotiations can also cost money, sour public opinion on their elected officials and school employees, and siphon off valuable time and energy.

And ultimately, it can all come crashing down in an instant. Case-in-point: the scheduled teachers strike on March 15.

Yes, teachers and board members will meet three times between now and then — the first negotiating session was scheduled for Tuesday night — but with both sides increasingly frusterated and willing to publically air their grievances, any new contract is far from a done deal.

No one can predict whether these last-ditch-effort sessions will produce a compromise that is palettable to both the district and teachers, and we won’t try.

What we will do is urge both sides to consider the best interests of students and parents in the district. Have they been best-served over the last four years, as negotiations produced nothing but angst, resentment and distraction? Would they be best-served if teachers hit the picket line rather than the classrom on March 15?

We say all that to say this: Pennsylvania needs a better, more expeditious way to formulate union contracts with the men and women responsible for helping educate our young people. If you think these protracted stalemates aren’t costing our state young, promising teachers, think again.

What we’re seeing play out in South Butler School District right now isn’t an exceptional case. It’s par for the course in Pennsylvania. That’s a problem we need to learn from and correct.