The federal government often works to limit state-to-state variation in how policies are enacted. How does the federal government encourage policy standardization between states

National standards, grants-in-aids, overriding power      

Explanation:

The federal government can standardize policies between states by setting national standards which the states are bound to comply with.

The federal government also ensures standardization by overriding states laws and policies that are inconsistent with federal policies.

The federal governments can also use grants-in-aids to compensate states whose policies are similar to those supported by the federal government thus causing other states to adopt those policies.

abraham lincoln issued the preliminary emancipation proclamation on september 22nd, 1862. it stipulated that if the southern states did not cease their rebellion by january 1st, 1863, then proclamation would go into effect.