Yes, it is true that this country is slightly more divided now then it has been in the past, but the issues are not that different. Here is a rough list of important issues by decade (give or take 5 years).
- 1780s and 1790s: Tax issues (Whiskey Rebellion), creating the nation, Supreme Court
- 1800s Louisiana Purchase, Slavery, staying out of English/French war
- 1810's War of 1812 (see English/french war above), Federal bank?, slavery, Keeping Europe out of Americas
- 1820's: Taxes, Banking, Indian removal
- 1930s': Financial crisis, Indian Removal
- 1840s: Fighting with Mexico about Texas
- 1850: Slavery, civil war coming
- 1860 Civil War/Slavery ends, Constitutional changes
- 1870s: Reconstruction, civil rights, Female suffrage
- 1880s: Corruption in government, gold standard, monopoly/labor strikes, Female suffrage
- 1890's Spanish American war, Hawaii, Gold Standard, Female suffrage
- 1900's: Trust busting, Female suffrage
- 1910's Trust-busting, federal income tax, corruption fighting, World War I (keep away from Europe), Female suffrage, prohibition
- 1920 's: economic issues - low taxes, then stock market crash, prohibition
- 1930: Depression, World War, prohibition (repeal)
- 1940's World War II,beginning of desegregation
- 1950's Korea, Cold War racism/civil rights
- 1960's Cold War, Civil Rights, Space program, Medicare and Medicaid, Vietnam, Abortion
- 1970s Nixon scandal, good buy Vietnam, goodby gold standard, Environmentalism, Salt I (nuclear proliferation), Abortion
- 1980's Anti-government, anti-=taxes, Abortion
- 1990's Gay rights become a real issue, Abortion
- 2000s Terrorism, attempts to cut entitlements Healthcare bill, gay rights, Abortion, Legalize Marijuana
- 2010 Gay rights, abortion, Legalize Marijuana
So at heart the four main issues have always been:
- Public Safety
There is one more issues that don't fit these four neat categories - specifically abortion. While on the surface it is a public safety issue with a dash of discrimination, it is dramatically different from all other issues.
Abortion is a relatively new issue that people feel strongly about and does not fit into those categories. It might end up being a new, re-occurring theme. Why is it so different? The other issues are all at heart answerable by science, but abortion can not be 'solved' by science.
The true heart of the abortion issue is what counts as a person. If you consider a just fertilized egg to be one, then abortion is killing babies. If you don't, then abortion is a simple surgical procedure similar to getting a vasectomy in that it prevents you from having unwanted children. But the question of person-hood is at best a philosophical one, or more likely a religious one. Science can not tell us the answer.
But lets get back to the big four long term issues government fights over
In general the economic battles tend to get settled. Eventually either people realize the new idea is garbage without trying it out, or they do try it out and it either works or fails. If it works they keep it, fails it gets over-turned. Then someone comes up with a new idea and the process starts all over again.
Prejudice appears to be the same battle fought repeatedly, slowly having the prejudiced people lose, then the anti-prejudice people move on to the next group that is being picked on. There is real progress being made consistently on that issue, from the original compromises allowing slavery all the way to the current fight about gay marriage.
War on the other hand seems to be a constant issue - staying out of them, or getting into them, there is no real progress made on the general issue, we just keep changing the name and location of the war.
Finally, Public Safety is a rather interesting question. This includes gun issues, drugs, alcohol, pollution, and healthcare in general. In general, this gets treated like economics. Slowly ideas get tested and then either accepted if it works or over-turned if it fails. Strangely enough, liberals and democrats fight over this a lot. If it is portrayed on moral grounds, the conservatives will spend money, otherwise the safety measures are considered 'too expensive'. Unless of course they think the safety measure itself is considered unsavory in some way (HPV vaccine), then they complain on moral grounds rather than economic grounds.
But it takes a lot longer to solve Public Safety issues and people keep bringing up failed ones (assualt weapons), while simultaneously people keep killing successful ones as well (background checks on guns).
The heart of the matter is that we really only have 4 main issues in American Politics, (plus abortion). Things are not all that different now than they 100 years ago when it comes to what we argue about.