What are two ways the u. s. constitution keeps the central government from being to powerful?

The first is that the Executive branch has a term limit associated with it. This ensures that no one Chief Executive can amass too much power or rule for too long.

The second is America's ingenious system of checks and balances which works to ensure that there are three co-equal branches of government instead of one lead branch and two subservient branches of government.

a big wall across the mexican border so no drugs, terrorist, or illegal immigrants can come through : )