Things to know
Today, dress in the U.S. tends to be fairly casual. For everyday clothes, jeans and T-shirts are always acceptable, as are shorts when the weather is suitable. Sneakers (athletic shoes) are common; flip-flops and sandals are also popular in warm weather. In the winter seasons in northern states boots are commonly worn.
At the workplace, business casual (slacks, understated collared shirts without a tie, and non-athletic shoes) is now the default at many companies; more traditional industries (e.g. finance, legal, and insurance) still require suits and ties, while others (e.g. computer software) are even more casual, allowing jeans and even shorts.
When dressing up for nice restaurants or upscale entertainment, a pair of nice slacks, a collared shirt, and dress shoes will work almost everywhere. Ties for men are rarely necessary, but jackets are occasionally required for very upscale restaurants in big cities (such restaurants will almost always have jackets to lend).
At the beach or pool, men prefer loose bathing trunks or boardshorts, and women wear bikinis or one-piece swimsuits. Nude bathing is not generally acceptable and is usually illegal except at certain private beaches or resorts; even women going topless is not usually accepted by most people, and is also illegal in some states.
Generally, Americans accept religious attire such as yarmulkes, hijabs and burqas without comment.
The United States has a higher proportion of religious adherents than many western nations, and visitors looking to attend services should have no problem locating a house of worship, even in small towns. A typical medium-sized American town or city probably has one or more Catholic parishes, several Protestant churches (the most common being Baptist, Pentecostal, Lutheran, Presbyterian, Methodist and Episcopal/Anglican), and other houses of worship depending on the demographics of the area (such as synagogues or mosques).
Most Christian churches in the United States practice an "open table", meaning they welcome you to participate in worship, and some or all rituals, even if you're not a member of their religious denomination. Some churches, and some entire denominations, welcome LGBT individuals.
Some of them also have after church luncheon for free or at a cost and you are always welcome to stay for lunch and fellowship as a way to meet locals.
News and media
Print media are not as ubiquitous as they were before the advent of the Internet, but print isn't dead yet. Just about every mid-sized city (and many small ones) has a daily newspaper covering local news and often some national news. Major metropolitan areas will usually have a number of papers to choose from, each with its own editorial slant and biases, but all of generally high quality of reporting. (A few exceptions, known as "tabloids" after their most common printing format, exist; you can identify them by their exaggerated, sensational headlines.)
The national paper of record is The New York Times ($2.50 daily, $6 Sunday); although ostensibly a newspaper local to New York City, its coverage of national and international issues makes it daily reading just about anywhere in the country. For financial news, The Wall Street Journal (also based in NYC, $2) is similarly well-respected and widely read. For a more casual but still informative format, USA Today ($2) publishes five days a week; it's the most widely circulated print newspaper in the country. Many hotels offer free copies of either the local paper or USA Today; ask at the front desk. Other widely read papers include the Los Angeles Times (noted for its West Coast coverage) and The Washington Post (with exemplary political reporting from the nation's capital). Newsmagazines like Time are published weekly and offer more in-depth feature coverage.
Major metropolitan areas also have a full suite of broadcast television stations; small cities might have only two or three local stations, especially if they're within broadcast range of a larger city. The major broadcast networks are ABC, CBS, NBC, Fox, and PBS (taxpayer-funded public broadcasting). You'll rarely be traveling anywhere that you'd need to use an antenna, though; almost the entire country is wired for cable TV. That opens up a whole range of options for viewing, from CNN for news to The Weather Channel to ESPN for sports, along with countless entertainment channels. The channel numbers vary based on the cable provider and location, which is why most hotels provide a channel listing. Most cable systems also have a program guide available through the cable box.
Broadcast radio is a much more fragmented market than television; major cities have dozens of stations on both AM and FM bands. The AM band is mostly used for talk formats, due to the lower sound fidelity; music stations are almost exclusively found on the FM band. The most popular radio music formats are Country, Top 40 (current hits), and Adult Contemporary (a blend of soft rock, easy listening, and the softer side of modern pop). Many rental cars come equipped with satellite radio from SiriusXM, which offers hundreds of channels of music, comedy, news, and sports, without the need to keep finding new stations as you drive across the country.