Grant’s Farm, owned by the Busch beer family, has long been a popular attraction in St. Louis County. Soon, it could become a national park.

The St. Louis Post-Dispatch reported this week that the National Park Service is studying the feasibility of purchasing the 273-acre St. Louis County animal preserve and private residence and turning it into a national park.

The newspaper says the service has completed an initial evaluation and examined the site’s national significance, how it might fit into the park system and its suitability as a national park. The evaluation did not make a formal recommendation and no timetable for a decision has been announced.

Grant’s Farm draws 550,000 visitors each year. It includes 100 species of animals ranging from elephants to monkeys and farm animals.

Admission is free, though there is an $11 parking charge.

The study is called a reconnaissance study. It is the first step in what can be a lengthy process of considering property as a national park or historic site.

The Busch family was described in the report as “very supportive of the property’s possible inclusion.” Grant’s Farm has been in the Busch family for more than 100 years. It has operated as an attraction for the last 55 years.

The family does not face any pressure to sell, said Frank Hamsher, a spokesman for the August A. Busch Jr. Trust, which owns the property and whose beneficiaries are six Busch siblings. And he said the brewery, which operates Grant’s Farm for the trust, has not pushed the family to sell.

“The family’s desire is for the long-term preservation of the entire Grant’s Farm,” Hamsher said.

The brewery said it is not involved in the discussions, but otherwise declined comment.

The future of Grant’s Farm has been in question since Belgium-based InBev purchased Anheuser-Busch in 2008. The merged brewery sold off Anheuser-Busch’s theme park and entertainment division, though Grant’s Farm is not part of that division.

The park service study estimated that Grant’s Farm loses $3.5 million to $4 million annually.

Grant’s Farm sits next to the 10-acre Ulysses S. Grant Historic Site, property once owned by the Civil War general and president. The park service report expressed confidence in the national significance and suitability of Grant’s Farm, which was once part of Grant’s land holdings and features two of his former residences — a cabin and villa. The historic site features the White Haven farm that Grant also called home.

The report expresses some concern about potential operational costs, and the cost of spending millions to buy the land and the animals.

Even if the Park Service decides to purchase Grant’s Farm, Congress can overrule the decision. In 2006, the park service rejected the designation of Great Falls in Paterson, N.J., as a national park, only for Congress to order its inclusion. It is now part of the parks system.

St. Louis-area lawmakers sounded supportive, but cautious about the cost.

The park service manages 392 sites.