The first spacecraft to land on the moon was Luna 2 in September of 1959. The first of our manned space missions to the moon occurred in December 1968 and was a simple orbit of the celestial body. Finally, in July of 1969, the first man set foot on the moon which was an incredibly momentous occasion not just for the USA, but for all of humanity. This was followed by five more moon landings over the next three and a half years. The final moonwalk occurred in 1972, and then all travel to space was suddenly cut off.
But why? You would think that after such a successful decade of space travel, that we would continue to push ourselves further outward into the unknown. The truth is actually quite simple and a little disappointing. It's just not economical. Putting billions of dollars of our national budget into something that has very little proof of returns just doesn't make sense.
The only reason that the USA and the USSR put so much money into space travel at the time, was due to the Cold War. Each country wanted to prove that they were more advanced technologically and it became a race to see who could get to space first. After the Soviet Union launched Sputnik in 1957, the US became very concerned that Russia would "conquer" space before them, and set aside a huge part of the national budget to found NASA and beat the Soviets to space. After the US proved that they had the moxie to beat Russia to space, it was soon realized that there was no real economic benefit to traveling to and from the moon, and the NASA budget was reduced significantly. The chances of any manned space missions beyond Earth's orbit became minuscule.
Now, we only participate in LEO (Low Earth Orbit) travel. The sad thing is that the USA doesn't even own the rockets that send satellites and people into space. Instead, if the US government wants to send something or someone to space, they must go through third party vendors. These can either be private businesses in the US, like Boeing or SpaceX, or other countries like Russia or Japan.
The US occasionally launches satellites into GEO (Geostationary Equatorial Orbit) and LEO when it benefits them. This includes cell phone, weather, GPS, and television satellites. These can be justified in the budget because there are countless economic, tactical and social benefits to them. The only people that are ever sent to space are the astronauts that go to the International Space Station. They go there to perform experiments that can only be performed in zero gravity, and their experiments are quite limited.
The only chance that we have of traveling out into our solar system resides in the private business sector. Elon Musk, co-creator of Paypal and CEO of Tesla, has ventured into the space game with his company, SpaceX. His mission is to reduce the cost of travelling to space low enough so that people can buy tickets on a shuttle to Mars. If he is successful, humans can look forward to traveling to space once more and children can dream of being astronauts once again.