In 1792, the act declared that, the president pro tempore of the Senate would be first in line for the presidency should the president and the vice president both be incapacitated. The speaker of the House was second in line.
The 1886 act replaced the president pro tempore and speaker on the list with the members of the president’s cabinet.
The order of succession reflected the order in which the cabinet positions had been created, with the secretary of state first in line after the vice president.
In 1947, the president pro tempore of the Senate and the speaker of the House were brought back in to the line of succession. This time, the speaker of the House was first in line behind the vice president, and the president pro tempore second in line. Members of the cabinet fill out the line as they did in the 1886 act, by when the cabinet positions were created.
Here is the line of succession for the United States government:
1. Vice President
2. Speaker of the House of Representatives
3. President pro tempore
4. Secretary of State
5. Secretary of the Treasure
6. Secretary of Defense
7. Attorney General
8. Secretary of the Interior
9. Secretary of Agriculture
10. Secretary of Commerce
11. Secretary of Labor
12. Secretary of Heath and Human Services
13. Secretary of Housing and Urban Development
14. Secretary of Transportation
15. Secretary of Energy
16. Secretary of Education
17. Secretary of Veterans Affairs
18. Secretary of Homeland Security