When properties go up for sale at a tax auction in St. Louis, they go to the city if they fail to get any bids. Over the past several decades the city has acquired thousands of parcels.

The numbers surged during the Great Recession, swelling the portfolio of the Land Reutilization Authority, which takes title of properties not sold at auction. The number of unwanted tax sale properties transferred to the authority jumped from 257 in 2007 to 854 in 2012, four times the number of properties investors bought that year.

But as the housing market has improved in recent years, that trend is reversing.

In 2015, 328 properties were purchased (excluding sales that were later invalidated) and 733 went to the authority, according to data from the city sheriff’s office. In 2016, fewer properties were auctioned off, but the number of sales held steady at 318. The authority picked up 499 more properties, the first time the figure dropped below 500 since 2008.

“Competition has definitely increased in 2016,” said Robert Vroman, the most prolific buyer at the five auctions the city holds each year. “I think there was record turnout at every auction.” Vroman estimates attendance has more than doubled since he went to his first auction in 2011, when about 80-100 people showed up.