(Nabil K. Mark/Centre Daily Times via AP)

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On Aug. 2, Canada dissolved its Parliament, clearing the way for new elections in October. The campaign — all 78 days of it — was an unusually long one for the country.

That same day, the U.S. presidential race, which formally began with Ted Cruz’s announced candidacy March 23, was 132 days old. During the period that Canada was holding its elections, the total change in the U.S. field was the addition of one candidate (Larry Lessig), bringing the total field to 20 major candidates (depending on whom you consider “major”). There were also two debates in that time. That’s it.

The first votes didn't happen until 315 days in, counting from when Cruz made his announcement. Candidates were informally campaigning well before his official entry, of course, and we still have several months to go.

So why are U.S. elections so long, when Canada finishes with its own so quickly?

Two reasons. The first is scheduling. The second is how hard it is to change.

I can tell you right now when the 2244 election will take place. It will be Nov. 5 that year. The United States has elections for the presidency every four years, like clockwork. November 2000, 2004, 2008, 2012, 2016, 2020 ... 2240, 2244. It's written into the Constitution, the document that structures the U.S. government.

That means the day after a new president is elected, we know precisely when he or she is going to be up for election again or when a successor will be picked if he or she hits the two-term limit.

The first mention of the 2016 race after President Obama was reelected on Nov. 6, 2012, was in the Boston Herald — on Nov. 7, 2012. The Herald's Kimberly Atkins talked to an expert: “ ‘I just don’t see [Mitt Romney, Obama’s Republican rival in that election] trying to make a comeback,’ presidential campaign expert Richard Benedetto said about 2016. “The 2012 campaign didn’t start in earnest until after the midterm elections in 2014 — but even that was about 730 days before the vote in 2016.”

In most countries that have elections, the process is different. In a parliamentary system, like Canada’s, new elections are called once the current parliament or government is dissolved, and the vote is only a few months later. That’s the election season, over almost as quickly as it began.

The United Kingdom decided to move away from this system, passing a law in 2011 setting fixed election dates, every five years. As Bloomberg News reported in 2013, that was in part meant to help political parties figure out how to stay within mandated spending limits. If this ends up being painful — as we can predict it will be — the British parliament can simply pass a new law to change it.

For the United States to change how it elects its president, it would have to amend the Constitution, a process requiring a huge amount of popular support and political cohesion and which hasn’t been done since 1971. Such a change would require either two-thirds majorities of the House and Senate or support from a constitutional convention called by two-thirds of the legislatures of the 50 states. Then, the amendment needs to be ratified by three-quarters of the states.

There’s not much incentive among politicians to change the electoral process. As in the United Kingdom, it’s beneficial for political parties to have defined timelines against which to plan. Plus, the parties have a lengthy primary process that states will be loath to give up, as it ensures that candidates will stop by to make a personal pitch to voters. With politicians, parties and states aligned against the idea, amending the Constitution seems pretty unlikely.