The index gained 42.47 points or 0.3 percent to close at 14,296.24.
"The market has momentum," said Russ Koesterich, global chief investment strategist at asset managing firm BlackRock Inc. "I think we go higher until you have an event that suggests things aren't as rosy as people think."
"There is this new found courage," said Erik Davidson, deputy chief investment officer of Wells Fargo Private Bank.
He told The Wall Street Journal the economy "is a lot less worse than people had feared."
Payroll firm Automatic Data Processing Inc. said Wednesday the economy added 198,000 private sector jobs in February -- the smallest gain in the past four months, but about 28,000 more than economists had predicted.
By close of trading Wednesday, the Standard and Poor's 500 index added 1.67 points or 0.11 percent to 1,541.46. The Nasdaq composite shed 1.77 points or 0.05 percent to 3,222.37.
On the New York Stock Exchange, there were 1,700 gainers and 1,347 stocks that lost ground, with 3.6 billion shares traded.
The 10-year U.S. treasury note fell 12/32 to yield 1.944 percent.
Against the dollar the euro was lower at $1.2975 from Tuesday's $1.3051. Against the yen, the dollar was higher at 94.09 yen from 93.29 yen.
In Tokyo, the Nikkei 225 rose 2.13 percent on a gain of 248.82 points, to 11,932.27.
In London, the FTSE 100 index shed 0.07 percent, 4.31 points, to 6,427.64.