Iowa: Amy Klobuchar (she's got the neighboring state bonus, which should help her here)
New Hampshire: Bernie Sanders if he runs, otherwise Elizabeth Warren (both have a neighboring state bonus, and both will likely be in top three in Iowa)
Nevada: Kamala Harris (Neighboring State and all)
South Carolina: Cory Booker (I can see Harris winning here, but I think Booker has stronger ties to the Black community. As such he'll be tougher to beat in South Carolina, as well as other Southern States).
Is the neighboring state effect an actual thing?
Voters are usually more familiar with candidates from neighboring states due to overlapping media markets. It's not necessarily a strong bond voters feel to the states next to them, but rather just a name recognition advantage. Also a lot easier for candidates to travel to/campaign in neighboring states rather than to have to fly/drive hours to get to events.
