What Makes up the United States?
The United States of America consists of 50 states, 1 federal district, 1 incorporated territory, and 15 unincorporated territories. 
50 States: 48 adjoining states plus Alaska (49th) Hawaii and (50th).
Federal District: Washington D.C.
Incorporated Territory: Palmyra Atoll
Unincorporated organized territories
- Northern Mariana Islands
- Puerto Rico
- U.S. Virgin Islands
Unincorporated unorganized territories
- American Samoa
- Bajo Nuevo Bank
- Baker Island
- Howland Island
- Jarvis Island
- Johnston Atoll
- Kingman Reef
- Midway Islands
- Navassa Island
- Serranilla Bank
- Wake Island
Extraterritorial Jurisdiction and Associated States
Aside from the major territories, the U.S. includes or has included a number of other locations including extraterritorial jurisdictions like Guantanamo Bay Naval Base (since 1903) and associated states like Federated States of Micronesia (since 1986), Marshall Islands (since 1986), Palau (since 1994).
There Have Also Been a Wide Range of Former Territories, Administered Areas, and Other Zones
Former territories include many areas of land that are now American states like “the Louisiana Territory” as well as some places outside the US. Formally administered areas include places like Haiti from 1915 to 1934, and other zones include sections of countries, such as South Korea during the Korean War.
This video shows U.S. boundaries and territories from 1763 – 2008.
Do Embassies and Bases Count?
When considering US bases and embassies abroad as “U.S. soil” America’s reach extends to many additional parts of the world.
However, According to the Foreign Affairs Manual, 7 FAM §1116.1–4: “Despite widespread popular belief, U.S. military installations abroad and U.S. diplomatic facilities are not part of the United States within the meaning of the 14th Amendment. A child born on the premises of such a facility is not subject to U.S. jurisdiction and does not acquire U.S. citizenship by reason of birth.” 
NOTE: There are Many Islands Under the Control of the US. You can see a full list of islands here.