Why have many family farms in North America been replaced by agribusiness farms since the 1980s?

Mostly due to Cost and Competition

Explanation:

Family farms were a common in Rural America and for generations, helped to support local communities.

A farmer and his family would work together to keep chicken, pigs, dairy animals and manage their land. It was simple living but the backbone of food supplies for urban areas.

However, industrialization and post-war boom in the US saw many corporation enter the Agriculture business and began factory farming at a scale never seen before.

The large investments helped to reduce cost and under cut many traditional family farms. Eventually, many farms lost money and the owners sold out and moved away.

Today, most agribusiness is controlled by large multinational corporations.