"We're using the word optimistic because we are actually optimistic," he added.
"The sun and moon and stars are lined up for a very successful year" in the U.S., he said the next day at a conference in San Francisco.
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"I don't see any weak spots in America," Dimon said, noting that corporations, small business, the stock market and the U.S. housing market are all showing signs of improving.
Outstanding loans to companies reached an all-time high of $1.61 trillion at the end of last year, topping a record set in late 2008, according to Federal Reserve data released on Friday.
Bankers say that anecdotally, business customers are more hopeful than they had been.
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"I am hearing more when I talk with customers about their interest in building something, adding something, investing in something," Wells Fargo CEO John Stumpf said on a conference call with investors last week. "There is more activity going on."
To be sure, signs persist that economic growth is still tepid.
Job growth slowed sharply in December, when U.S. employers hired the fewest workers in nearly three years, partly because of winter storms. And while holiday sales rose 0.2 percent in December, it was at the cost of heavy discounting by retailers.
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But the U.S. grew at a relatively fast annualized 4.1 percent in the third quarter, and General Electric—often looked to as a barometer of the health of the U.S. industrial sector—said on Friday that it had record orders for jet engines, oil pumps and other industrial goods.
"We have seen some moderate strength in the U.S.," GE Chief Financial Officer Jeff Bornstein said in an interview, even if he cautioned that the company has not yet seen "the breakout broadly across the economy."
Bornstein said the company's strong backlog reflects the growing middle classes in emerging and developing countries around the world.
"We see solid demand for loans as we head into 2014" from businesses, particularly large corporations and healthcare companies, along with owners of commercial real estate, Bank of America CFO Bruce Thompson said on a conference call with analysts on Wednesday.
U.S. consumer loans, including mortgages and credit cards, also have been steadily rising since early 2011, according to Fed data.
Analysts on average forecast U.S. growth of 2.9 percent in 2014, close to the long-term average for the United States but a bit stronger than in recent years.
Credit is the lifeblood of the economy, and lending volume has been relatively weak since the financial crisis. Some economists fault banks for holding onto the purse strings too tightly, while others fault companies and consumers for being too timid to spend.