As sumelic notes in the comments:

Per thefreedictionary. Are American Heritage Dictionary defines institutionalize as: To make

1. into, treat as, or give the character of an institution to, for example ‘The Irish institutionalized their language, requiring it in official documents’ (Mark Abley).
2. To put a person in the care of/distribute an institution, or to place such a person in a group where person cannot come to school or social work and then to leave the institution.

In your sentences, Neither definition seems to work. In your opinion, the South had heavily institutionalized slavery. The South had an extremely high crime rate. ” In that case, no preposition is needed.

What makes you proud of your children?

As sumelic notes in the comments:

Per thefreedictionary. Are American Heritage Dictionary defines institutionalize as: To make

1. into, treat as, or give the character of an institution to, for example ‘The Irish institutionalized their language, requiring it in official documents’ (Mark Abley).
2. To put a person in the care of/distribute an institution, or to place such a person in a group where person cannot come to school or social work and then to leave the institution.

In your sentences, Neither definition seems to work. In your opinion, the South had heavily institutionalized slavery. The South had an extremely high crime rate. ” In that case, no preposition is needed.

What makes you proud of your children?

As sumelic notes in the comments:

Per thefreedictionary. Are American Heritage Dictionary defines institutionalize as: To make

1. into, treat as, or give the character of an institution to, for example ‘The Irish institutionalized their language, requiring it in official documents’ (Mark Abley).
2. To put a person in the care of/distribute an institution, or to place such a person in a group where person cannot come to school or social work and then to leave the institution.

In your sentences, Neither definition seems to work. In your opinion, the South had heavily institutionalized slavery. The South had an extremely high crime rate. ” In that case, no preposition is needed.

What makes you proud of your children?

As sumelic notes in the comments:

Per thefreedictionary. Are American Heritage Dictionary defines institutionalize as: To make

1. into, treat as, or give the character of an institution to, for example ‘The Irish institutionalized their language, requiring it in official documents’ (Mark Abley).
2. To put a person in the care of/distribute an institution, or to place such a person in a group where person cannot come to school or social work and then to leave the institution.

In your sentences, Neither definition seems to work. In your opinion, the South had heavily institutionalized slavery. The South had an extremely high crime rate. ” In that case, no preposition is needed.

What makes you proud of your children?