Why would President Washington warn the country to avoid sectionalism?

He warned the country to avoid sectionalism because of the rise of political parties and sectionalism as a threat to national unity.

Explanation: Well , Washington warned the people that political factions may seek to obstruct the execution of the laws created by the government or to prevent the branches of government from exercising the powers provided them by the constitution.

because political factions may seek to obstruct the execution of the laws created by the government or to prevent the branches of government from exercising the powers provided them by the constitution.

Explanation:

a. favoring native born americans over immigrants.