• 270 Electoral College Votes required to win

• Seven competitive states will decide presidency

• Will these betting signals prove superior to polls?

• Follow our 2024 US Election live blog here

The first rule of US election betting is to understand, calculate and predict the electoral college. This determines the presidency - as opposed to the popular vote. Indeed, Donald Trump won in 2016 despite losing the popular vote to Hillary Clinton by nearly 3M votes.

Electoral College basics

Each of the 50 states awards a set number of electoral college votes (ECVs). For example, California awards 54 ECVs, Texas 40, Alaska 3, while the congressional districts in Maine and Nebraska award one each. The total is 538, which makes the winning line 270. 43 of the states appear to strongly favour one party, leaving the balance of power with the remaining seven.

At least once, probably several times per day from now until November 5th, hardcore US Election bettors will be on the lookout for polling model projections, especially from these swing states. These are essential research material, for sure, but beware reading too much into the averages at this relatively early stage in the campaign.

Key differences between polls and betting odds

As it stands, Fivethirtyeight's average for Harris and Trump amounts to 91%. I will be shocked if their actual tally is less than 97%. Polling averages will only reflect that when the number of undecideds fall.

Plus of course, so much can and will change over the next ten weeks. The key difference between polls and betting is that whereas the former is a snapshot, betting odds are forward thinking. We are taking odds now with a view towards predicting the future trajectory of the market, and result. Bettors are already estimating where those undecideds end up.

Polling averages and models will definitely impact the betting but they won't mirror it. In 2020, for instance, Trump's percentage chance implied by Betfair odds was around double that of Fivethirtyeight during the final weeks. Neither or any methodology here is perfect, and we will doubtless compare the results afterwards.

Building a map based on betting odds

One useful website for calculating the electoral college is 270towin.com. The interactive map on their home page shows their current projection and grading for each state. The darker shade of red, the stronger the Republican chance, or blue for Democrats. Their current forecast below is incomplete as five states are deemed 'toss-ups' (in grey). You can alter the grading to match your own projection. Here's their current map.

Could Betfair odds prove a better guide, or provide earlier, more conclusive signals regarding these toss-ups? Let's monitor it by employing this new ratings system, based on the odds with the following grading. (Note that no state has ever been lost from below 1.11/10, hence the 'Solid' label).

Any state where the favourite is trading at 1.7 or higher = TOSS-UP
Any state where the favourite is between 1.4-1.69 = LEAN (to that party)
Any state where the favourite is between 1.1-1.39 = STRONG LEAN
Any state where the favourite is below 1.1 = SOLID

Latest odds in toss-up/lean states as of 26/08/24

ARIZONA: REPUBLICANS 1.9, DEMOCRATS 2.1

GEORGIA: REPUBLICANS 1.62, DEMOCRATS 2.54

MICHIGAN: DEMOCRATS 1.57, REPUBLICANS 2.74

NEVADA: REPUBLICANS 1.94, DEMOCRATS 2.06

NORTH CAROLINA: REPUBLICANS 1.64, DEMOCRATS 2.54

PENNSYLVANIA: DEMOCRATS 1.94, REPUBLICANS 2.06

WISCONSIN: DEMOCRATS 1.68, REPUBLICANS 2.46

Based on today's odds, that means Michigan and Wisconsin are 'Lean Democrat'. Georgia and North Carolina are 'Lean Republican'. Arizona, Nevada and Pennsylvania are 'Toss-ups'. It produces this map. Remember, 270 ECVs are required to win.

The map almost perfectly reflects the current signal from the betting - that the presidency is effectively a toss-up. An even race. Even the four 'lean' states are only just outside the 'toss-up' category, and could move into it with the smallest of betting moves.

Moving forward, a key angle for bettors to find value is to check whether the Election Winner odds correlate with these state projections. Right now, that appears to be the case. I will frequently refer to this in our US Election Live Blog to monitor the state of play, and identify any divergence.

Now read US Election 2024: Senate polls imply Harris will increase her advantage