I have crossed borders with Electrum installed on my smartphone and PC but no one has ever asked me anything.
If no one knows, that means that it didn't happen, which means no need to declare anything.
That's the wrong approach. I always declare everything I have to, up to an apple in some countries. If it's not allowed, I'll throw it away. But at least I won't get into any kind of trouble.
I forgot about this reply, I found it out today, so pardon me for asking it right now.
Why is this a wrong approach? We talk about Bitcoin, it's virtual. I travel multiple times throughout a year (inside the EU, mostly, sometimes in the UK and once was in the USA a few months ago to watch UFC fight). I have never ever said anything about my Electrum wallet and Bitcoins. Seriously, why should I declare, why is this a bad approach? It's on my laptop and smartphone, who will ever know? Will anyone ever ask me to turn on my laptop and unlock it? This hasn't happened ever in my case and I would have travelled at least 100 times in my life.
By the way, I never carry something that requires prescription and if there is anything in the future that's not allowed in the country, of course, I'll declare that but I have never thought about declaring my cryptos in Electrum wallet.
Maybe if I had to travel in certain countries like China, Russia, Belarus, North Korea, Iran, Sudan, I'd declare but I think I'm quite safe inside the EU, UK, USA and Canada, am I right? (I know that Australian customs are crazy).