I'm curious the reason why it was ever held in the US and Canada

Besides the reasons listed by the others, this also a matter of relationships as there a deep ties between these nations and the Netherlands. Without the Dutch financing the Americans, America would not have been able to become independent from the English. The Dutch were also the first country on earth to acknowledge America's independence [1][2], costing them a war with the pissed England [3].

There are a lot of Dutch people living in Canada.[4]

  _____

2. <https://en.wikipedia.org/wiki/The_First_Salute>

3. <https://en.wikipedia.org/wiki/Fourth_Anglo-Dutch_War>

4. <https://en.wikipedia.org/wiki/Dutch_Canadians>

It's mostly historical and a combination of security from the WW2 and Cold War eras as well as how the gold standard worked before Bretton Woods.

Most countries held gold reserves as their currencies were backed by it. When money needed to move because of trade, the ratios of currencies backed by gold would shift as money got converted to other currencies. However, constantly moving physical gold back and forth with the ebs and flows of trade was impractical, so ownership of gold in central bank vaults usually just had its legal ownership marked on ledgers. Physical gold moving was more part of reconciliation. This description is an oversimplification as in practice, countries didn't always play by the rules of the gold standard (revaluations, going on and off the standard, etc), but you get the general idea.

This mostly ended as Bretton woods came into effect and the new system was basing the US dollars on gold, then other countries held direct US dollars and traded that instead. Countries could then convert those US dollars into gold. This ended when Nixon closed the gold window when he refused to raise interest rates as there started to be a run on gold as countries rushed to convert. The backdrop was that high spending on the Vietnam was and new social programs was driving inflation, but Nixon knew that would cause an economic slowdown he wasn't willing to do. Jimmy Carter then took a lot of the political flack for allowing the central bank to raise rates to kill it. This is why central bank independence is so important.

During times of geopolitical risk, countries would physically move their gold to be held in trust in friendly and/or rule of law countries. The USA was seen as this between ~1914-now.

Makes trade easier than shifting currency. It’s also more stable and liquid if you need to make things happen in an emergency.

> I'm curious the reason why it was ever held in the US and Canada

Random Educated Guess; Probably part of some show of mutual trust to cement a treaty or other agreement, made way back when allied governments could mostly trust one another to hold to such agreements somewhat reliably?

Makes it harder to steal.

Don't forget that the European continent has had wars almost non-stop for centuries. It is a good strategy to place your gold in a location that has not seen much action in the past 250 years.

I would assume WWII and the Cold War?

(another guess) to convert to dollars, the gold would need to be delivered to the custody of the US Fed, which is easiest when the bars are physically in the Fed's vault. in a low-trust situation, you have all the gold in your own country, but then its so much leas liquid bc you need to physically deliver it to trading partners, or they must trust your accounting of their share in your vault.

Could be due to the fact that before 1970s the currency was backed by Gold and they had it in US to easily convert it to USD if needed

It was originally payments owed to Dutch interests in America being converted to gold and stored locally on their behalf, as opposed to having to be transported across the Atlantic back to the Netherlands.

Then later the Dutch moved a lot more of their gold over there before/during WWII in order to keep it out of reach of the Nazis.