He said he often saw bears strolling through the meadow and owls soaring over fields of vibrant wildflowers blooming in the springtime. He didn't want that experience available only to those who could afford a resort.
"To have that accessible by everyone to me is just a great thing," Wainwright said. "It was worth losing a little bit of money for that."
The park's boundary has seen some minor changes over the years, but this expansion is the largest since 1949 to the park of nearly 750,000 acres (303,515 ha) total, he said.
More than 4.5 million people are expected to visit Yosemite this year, which spokesman Scott Gediman said would set a record for the park that celebrated its 125th anniversary in 2015.
Visitors pass Ackerson Meadow on their way to Hetch Hetchy reservoir, which provides drinking water to San Francisco.
The land was bought with US$1.53 million ($2.05 million) from the Trust for Public Land and US$520,000 ($697,000) from the Yosemite Conservancy, which supports a variety of projects in the park. Anonymous donors contributed the rest, Gediman said.
"We are delighted and proud to make this gift to Yosemite and the people of America," said Will Rogers, president of the Trust for Public Land.
The land completes the park's original plans from 1890, which included Ackerson Meadow, said Yosemite Conservancy's President Frank Dean.
"It's a stunning open meadow surrounded by forest habitat, which supports a wide variety of flora and fauna," said Park Superintendent Don Neubacher.
- AAP