Your question presupposes a truth in the current tense. Well the US has been declining since the 70s, and today they are not great. Giving defacto citizenship rights to illegal, and refugees that don't really want to be Americans. Dilutes greatness.
Not to long ago, for example, illegal aliens protested in the streets of Los Angeles. They burnt American Flags while flying the Flag of Mexico. When foreigners came "illegally" come into the US or overstay their Visas and demand the US do anything is not a sign of a Great America.
The 1st Amendment allows the peaceful assembly, but looking at most of the protests that wind up in riots, this is not a 1st amendment right, even for the citizens of the US.
A great country protects its citizens, unlike 1993, 2001, 2015. On 911, not a single effective defensive action was waged by the trillion dollar plus Military, National Intelligence agencies and any other group that is funded to protect us. A great country doesn't let 19 terrorists on a very low budget take down the WTC, and 3,000 people. As well as damaging the Pentagon. With Andrews AFB nearby.
The 1956 National Highway System created by president Dwight D Eisenhower is no longer functional. In general none of our infrastructure has even been maintained much less improved.
FEMA didn't help in any of the "Acts of God" did they.
The latest rain storms in drought ridden California turned out to be a big disaster for Lake Orville, and its dam. Both the Federal and California govt knew years ago about the problem, and both decided not to do anything.
We have a government that spies on its own people because they couldn't stop 19 terrorists. Is that a great country. Because of that failure, people are treated like terrorists at the airport. And the sad thing is that there are so many soft targets here that this will fail to protect us. As we have seen in San Bernardino, and Orlando.
The national intelligence agencies failed in 2001, and 2004, and most everything they do. Is it failure or their goal?
The problem is that there a only Reactive while the terrorists are proactive.
Putting American Citizens in second place to illegal immigrants, and refugees is not a great country. Mexico doesn't let them in from their southern border, but they want us to it. They also can't or won't stop the $biilions of illegal drugs, human trafficking, and contraband coming from their Mexican to US border.
What will actually make America Great is pres Trump!
del if u wsh