John Nance Garner, FDR's first vice-president, is famously remembered for calling his office "not worth a bucket of warm spit" (although Garner actually used a more colorful example). And, yet, there is clearly some electoral value in the office—as nine vice-presidents have ascended to the presidency. Presumptive Democratic nominee Joe Biden aspires to be the tenth—and there's been a lot of recent focus on who his running-mate might be. Biden has committed to choosing a woman—and the pundit-generated short list has included: Stacey Abrams (GA), Kamala Harris (CA), Gretchen Whitmer (MI) and Amy Klobuchar (MN). We've added the states of the candidates, because the conventional wisdom is that VP picks help deliver their home states to the ticket—the so-called "home-state advantage". Of course, like much political "wisdom", this is pure bunk.
In fact, in 2016, POLITICO offered a thorough analysis of this issue by political scientist Kyle C. Kopko. His conclusion was that: "a presidential ticket performs no better in the vice presidential candidate’s home state than we would expect otherwise. Statistically speaking, the effect is zero". The analysis was written before the 2016 election—so Tim Kaine's impact on carrying Virginia for Hillary Clinton is not considered. In fact, the Democratic ticket carried Virginia by just 212, 030 votes (out of 3.75 million). However, despite adding Old Dominion's 13 Electoral College votes, Clinton lost to Donald Trump because states like Wisconsin, Pennsylvania and Ohio went for the GOP. So, while Kaine's presence on the ticket was helpful, it was not decisive.
So, it appears that presidential nominees would be better served by considering running-mate attributes other than geographical ones. For example, their ability to step in and capably serve as President at a moment's notice.