Final answer:
Without specified data, it's not possible to provide the 1999 midseason batting averages for American League teams. To calculate a team's baseball batting average, the total number of hits and at-bats until the midpoint of the season are needed.
Step-by-step explanation:
I'm sorry, but the specific data for the batting averages of teams in the American League at about midseason in 1999 is not provided in the given resources. Generally, to calculate the batting averages of a team, you would need to know the total number of hits and at-bats up until the middle of the season. Also, keep in mind that variability such as player performance, weather conditions, and team morale amongst others can cause fluctuations in team averages.
Learn more about Batting Averages