It's a bit different this time around. CONCACAF (the confederation for north and central America) has 35 teams. 8 compete in the final round: the top 5 by world FIFA rankings, and 3 of the remaining 30 who emerge from playing each other.
The 5 byes went to: Mexico, USA, Costa Rica, Jamaica, and Honduras. The 3 who won their way in were Canada, El Salvador, and Panama.
So now the 8 teams in the final round play each of the other 7 home and away, for a total of 14 qualifying games. You get 3 points for a win, 1 point for a tie, and 0 for a loss. At the end, the top 3 point getters make the World Cup, and the 4th place team goes into a separate inter-confederation playoff where teams from all over the world that just missed out on qualifying play each other for the last few World Cup spots.
So USMNT's goal is to finish in the top 3 of this 8-team tourney right now. Halfway through, we are tied for 1st with 14 points. Mexico also has 14, and Canada has 13. Panama has 11, and no one else has more than 6. We are in very good shape to avoid falling out of the top 4, but we would really rather stay in the top 3 to avoid that second playoff against non-CONCACAF teams.