The closing of the sale on Wednesday of New York's famed Waldorf Astoria hotel to China's Anbang Insurance Group Co Ltd for $1.95 billion marks the tip of an unprecedented wave of Chinese investment pouring into U.S. hotels.

The closing comes on the heels of Monday's announcement that another insurer from Beijing, the Sunshine Insurance Group, will purchase the luxurious Baccarat Hotel New York for $230 million.

Investment from mainland China into U.S. hotels is expected to be about $5.1 billion this year, or triple the amount over the previous four years, according to JLL, a global real estate broker and advisory services company based in Chicago.

Chinese investment into hotels has been growing since 2011 and 2012, when just $160 million and $130 million were invested, JLL data shows. The forecast represents 7.5 percent of the $68 billion expected for 2015 in cross-border hotel investments.

"We've never seen Chinese activity at this level in hotel real estate," said Gilda Perez-Alvarado, head of Americas for JLL's global hotels desk, which facilitates cross-border transactions. "It's unprecedented in terms of the amount of money coming from Chinaspecifically into the U.S."

The purchase announced in October of the Waldorf Astoria from Hilton Worldwide Holdings Inc (HLT.N) caught the industry by surprise, even in the midst of large Chinese investment into gateway U.S. cities such as San Francisco, Los Angeles and Seattle, andglobal markets like London, Paris and Sydney.

Slowing urbanization and a weakening economy in China have pushed Chinese companies to diversify abroad. The United States is the prime candidate for Chinese investment abroad because of a growing economy and the perception the country is safe, said Li Chen, a vice president with HVS, a hotel and leisure consultant.

"Chinese insurance and real estate companies are looking at the gateway cities and they will continue to invest in the United States, Chen said.

While the overall purchase price for the Waldorf Astoria is a headline grabber, the price-per-room - the figure the industry watches - was relatively low at $1.38 million a room, according to STR Analytics.

The Baccarat, the first of several hotels to be branded with the name of the famous French crystal, sold for more than $2 million a room. Private equity firm Starwood Capital Group sold the hotel, which is expected to open the first week of March.

When the family of Hong Kong billionaire Cheng Yu-tung bought five luxury hotels, including the Carlyle Hotel, for about $570 million in 2011, the price per room for the famed Manhattan hotel was $1.68 million, STR said.

Perez-Alvarado also said that while many talk about China because of the big push from the Chinese insurers, "the reality is that we are seeing a very deep pool of wealth coming from Asia in general, not just China, into the U.S," she said.

Dalian Wanda Group (3699.HK), China's biggest commercial real estate conglomerate, in August beat out more than 10 bidders from Asia and North America for a plot of land in Beverly Hills it plans to develop for $1.2 billion.