At least land-area wise it is. It’s just a little bigger than New Mexico (128k mi2. versus 121k mi2.) but it’s longer than California. Vietnam spans almost 1,000 miles north to south, while California spans about 750 miles. Here, I tried to make this close to scale:
I love maps. I think It’s because every time I look at one I learn something new. Also, depending on how they’re designed, they make me notice different things. Here’s a pretty one of Vietnam I just found:
O hi, Asia! 
I love maps too. High five! 😀