Great question. My experience visiting this museum, it's one of the busiest on the mall. I take family and friends there often. I always like to get 15 - 30 minutes early to beat the crowds.
10am for sure. All the museum's tend to get busy from like 12 to 3ish. However, at this time of year the lines look big but I never waited more than 10 mins.
10am would be the best time. Simply because there might be a line outside the doors. Also they close at 5:30 p.m..
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