Visits to top-tier indoor shopping malls across the United States fell 6.5 percent in September amid rising COVID-19 cases and as kids returned to school, according to the September mall index from analytics firm Placer.ai. The mall index focuses on 100 top-tier malls and 100 outdoor centers across the United States. Shoppers had returned to malls in droves in July, with visits to indoor malls rising 1.0 percent above the same month in 2019, in part due to a lack of travel and general excitement about the retail industry reopening after months of lockdowns. But things began to quiet in August, when those numbers dipped by 2.5 percent. And the declines continued into September, when visits to outdoor malls declined by 5.2 percent. However, experts are still optimistic about the future, noting that this summer’s “artificial” influx of shoppers was down to a “unique mix of factors” and was inevitably set to decline. While …