Why does 280south turn into 680 north in san jose, california?

Answer 1

Because that's how they built it. The 80 in the name means it eventually meets interstate 80. 280 meets it in Sa Francisco, and 680 meets it near Fairfield. At some point I suppose it seemed like a good idea to join the two together.

Answer 2

I have lived in the Northbay for 17 years, and I still find all the highways, whether it be 280, 680, 780, 880, 80, 580, or 37 very confusing.