Federal officials said they were working to address the website problems as quickly as possible. People contacting the federal call center also reported long wait times.
"We have built a dynamic system and are prepared to make adjustments as needed and improve the consumer experience," Health and Human Services spokeswoman Joanne Peters said.
State-operated sites also experienced glitches. Rhode Island's site opened as scheduled, but was quickly overwhelmed by visitors and went down. Sites for Maryland and Minnesota were not expected to open until at least midday.
Exchange officials in Colorado said their website would not be fully functional for the first month, although consumers will be able to get help applying for government subsidies during that time.
In Portsmouth, N.H., Deborah Lielasus tried to sign up for coverage but got only as far as creating an account before the website stopped working. She said she expected glitches.
Lielasus, a 54-year-old self-employed grant writer, currently spends about $8,500 a year in premiums and more than $10,000 for out-of-pocket expenses because she has a health condition and her only option was a state high-risk insurance pool. She said she expects those costs to decrease significantly when she's able to sign up for insurance on the marketplace.
As excited as she was to sign up, she said, her anticipation was tempered by dismay over the government shutdown that was led by congressional Republicans who want to block the health insurance reforms.
"I'm really happy that this is happening, that this is being launched ... I feel like it's a child caught in the middle of a really bad divorce," Lielasus said.
Despite the first-day hitches, insurers and advocates pushed the message to consumers about the new health insurance options.
Employees of Independence Blue Cross converged on four of Philadelphia's main train transit hubs Tuesday to distribute information and answer questions about the new exchanges.
At Suburban Station downtown, the company gave out more than 7,000 calendars marked with important insurance-related dates — starting with Oct. 1, the first day consumers can buy policies.
Ralph Kellum took a calendar even though he's already covered through his employer, the local transit agency. He said he knew a lot of people who would be interested in getting insurance.
"A lot of people ... (who) have the pre-existing problems, couldn't get insurance, now they can," Kellum said. "Well, supposedly they can."
The nationwide rollout comes after months of buildup in which the marketplaces have been both praised and vilified.
The shutdown will have no immediate effect on the insurance marketplaces that are the backbone of the law, because they operate with money that isn't subject to the annual budget wrangling in Washington.
The marketplaces represent a turning point in the nation's approach to health care, the biggest expansion in coverage in nearly 50 years.
The Obama administration hopes to sign up 7 million people during the first year and aims to eventually sign up at least half of the nearly 50 million uninsured Americans through an expansion of Medicaid or government-subsidized plans.
But if people become frustrated with the glitches in the computer-based enrollment process and turn away from the program, the prospects for Obama's signature domestic policy achievement could dim.
"The promise of the law is that no one will go bankrupt because of medical bills," said Neera Tanden, president of the Center for American Progress, which helped work for passage of the law. "It won't happen in the first day or the first year. But when the law is fully operational, it will provide an economic benefit to roughly 30 million Americans."
Tanden cautioned against rushing to judge the marketplace's success on its first-day performance. Numerous observers had predicted bugs and setbacks. Trained outreach workers in many states are having trouble getting the certification they need to start helping people to enroll.
Many states predicted that an initial surge of interest would test the online system, but they expect most people to sign up closer to Dec. 15, which is the deadline for coverage to start Jan. 1. Customers have until the end of March to sign up in order to avoid tax penalties.
Looming as one of the biggest challenges to the law's success is the ability of insurers to persuade young and healthy people to buy insurance to balance the costs of covering the older and the sick.
"You've got to launch this thing right the first time," said Robert Laszewski, a consultant who worked 20 years in the insurance industry. "If you don't, financially you will never recover."
Under the law, health insurance companies can no longer deny coverage to someone with a pre-existing medical condition and cannot impose lifetime caps on coverage. They also must cover a list of essential services, ranging from mental health treatment to maternity services.
Another obstacle: Nearly three-fourths of people under 65 who lack insurance are unaware that the marketplaces open Tuesday, according to a Kaiser Family Foundation survey released over the weekend.
Spending money to raise that awareness with ad campaigns has varied vastly, with some Republican-led states doing little or nothing to promote the insurance exchanges. Missouri Lt. Gov. Peter Kinder, a Republican, even recently urged residents not to sign up for coverage.
In Florida, Republican Gov. Rick Scott and key lawmakers have pushed back against implementing parts of the law. The Florida Department of Health recently ordered county health departments to prohibit so-called navigators from signing people up for health insurance at those facilities.
But other states are doing more, such as Kentucky, the only Southern state running its own marketplace. Kentucky Gov. Steve Beshear, a Democrat, was an early supporter of the health law.
The state kicked off an $11 million advertising campaign in June, with ads on TV, radio, Internet and newspapers. It will expand Tuesday and continue through the first three months of next year.
"Frankly, we can't implement the Affordable Care Act fast enough," Beshear said.
___ Associated Press writers Kelli Kennedy in Miami; David Lieb in Jefferson City, Mo.; Kristen Wyatt in Denver; Kathy Matheson in Philadelphia; Erika Niedowski in Providence; Holly Ramer in Portsmouth, N.H.; and Roger Alford in Frankfort, Ky., contributed to this report.
___ AP Medical Writer Carla K. Johnson can be reached at http://www.twitter.com/CarlaKJohnson
___ Online: https://www.healthcare.gov
The exchanges are starting up just as most of the federal government is shutting down, left unfunded by a Congress that's still bitterly divided about whether to discard Obama's health care law altogether.
The president planned to address both developments from the Rose Garden Tuesday afternoon, shortly after meeting privately with people who plan to purchase insurance through the exchanges.
The president's schedule is moving forward as the White House staff has been cut to one-quarter its normal size, with 436 reporting to work and the remaining 1,265 on furlough due to the first partial shutdown in almost two decades.
"Unfortunately, Congress has not fulfilled its responsibility," Obama said in a video message the White House released just after midnight Tuesday, as Congress missed its deadline to keep the government running. "It has failed to pass a budget and, as a result, much of our government must now shut down until Congress funds it again."
At the heart of the disagreement over a temporary measure to fund the government was whether Obama's health care law should be allowed to go into effect as written. House Republicans, cheered on by tea party-backed Republicans in the Senate, sought to defund or delay parts of the bill, arguing that once Americans started enrolling in the exchanges, the law becomes harder to repeal.
"The notion is, we've got to stop it before people like it too much," Obama said on NPR News. The interview was taped Monday and aired Tuesday.
Obama has insisted he wouldn't sign a bill that gutted the law, his signature legislative achievement. Lacking funding from Congress, the White House budget office told agencies shortly before midnight to start closing their doors.
In a bit of irony not lost on the law's proponents, the main components of "Obamacare" will move full speed ahead despite the shutdown that is shuttering national parks, veterans' centers and other government operations until Congress finds a way to break the stalemate. That's because funding for the Affordable Care Act, like other "mandatory" functions such as Social Security, air traffic control and national defense, is protected from the whims of Congress.
In addition to his own appearance, Obama will deploy top deputies to spread the message, the White House said. Vice President Joe Biden will appear on college radio stations. First lady Michelle Obama is publishing an editorial on a women's lifestyle website. And Obama's senior adviser, Valerie Jarrett, and other officials will be guests on African-American radio shows.
Tuesday's events coincide with the digital ribbon-cutting for the exchanges, which will allow Americans to compare and purchase insurance online. The Obama administration needs millions of Americans - mostly healthy, younger people - to enroll to keep costs low for everyone.
Republicans have seized on a list of technical glitches and delays that have emerged as evidence the law isn't ready to work and will never be. But the White House says that's true for any big, new program and won't affect the outcome, since Americans have six months to enroll through the exchanges.
"I would suspect that there will be glitches. This is 50 states, a lot of people signing up for something. And there are going to be problems," Obama said. "But what we're confident about is that people will be able to take a look and find out whether this is something that is going to be good for their families."
In his sole response to the shutdown early Tuesday, Obama directed his comments not at the lawmakers he's been scolding for weeks, but instead to the military. He made no reference to Republicans or Democrats, but his frustration was clear as he contrasted the professionalism and courage of American troops with lawmakers' inability to fulfill what he's described as their constitutional duty.
"You and your families deserve better than the dysfunction we're seeing in Congress," Obama said in the video message.
--- Reach Josh Lederman on Twitter at HTTP://TWITTER.COM/JOSHLEDERMANAP
An Ellisville man who broke into his ex-girlfriend's home and attacked her small dog so severely that the animal had to be euthanized, was sentenced to eight years in prison Monday. In July, a St. Charles jury found Charles Zidek guilty of felony charges of animal abuse and burglary. St. Charles County Circuit Judge Rick Zerr gave the 37 year old Zidek a four-year term on each charge, to run consecutively. Prosecutors say Zidek entered the home of Diana Walkonis in October, 2011, by breaking out a basement window. Authorities say he then repeatedly threw her Italian greyhound, Vinny, against a bedroom wall. Walkonis found her pet when she returned home later that day. Zidek was linked to the crime when by blood found in the house near the broken window, matched his DNA.