The final All-Star roster spot in each league is of course determined by online fan vote. It's called the Final Vote, and the balloting runs through 4:00 p.m. ET on Wednesday. As for the early returns, here's an update on the results thus far:

So if current voting trends hold, Jesus Aguilar of the Brewers will be an All-Star for the first time in his career, and Jean Segura of the Mariners will make it for the second time. MLB did not disclose the vote totals, so we don't know how tight these races are. 

As for the AL and NL All-Star rosters, which now stand at 31 players apiece, you can check those out here