So I'll begin with a few zoos that I know keep lemurs.
Brazil:
Sorocaba zoo - Ring tailed lemur (non breeding group kept at the zoo), Crowned lemur (also once held here and the taxidermy specimen of this individual is now displayed in the zoos museum).
Sao Paulo aquarium - Ring tailed lemur (non breeding group kept at the aquarium).
Zoo Itatiba - Black and white ruffed lemurs (small breeding group kept here), ring tailed lemurs (small breeding group kept here).
Brasilia zoo - Ring tailed lemur (unknown amount kept here).
Mexico:
Chapultepec zoo - Ring tailed lemur (small breeding group held here).
Guadalajara zoo - Ring tailed lemur (small breeding group held here).
Morelia zoo - Ring tailed lemur (small breeding group held here).
Zoo Leon - Ring tailed lemur (large breeding group held here).
Zacango zoo - Ring tailed lemur (small breeding group held here).
Africam safari - Black and white ruffed lemurs (small breeding group held here), ring tailed lemur (small breeding group held here).
Centenario zoo - Black and white ruffed lemurs (unknown amount kept here), ring tailed lemurs (unknown amount kept here).
Colombia :
Cali zoo - Black and white ruffed lemurs (small breeding group kept here), ring tailed lemurs (small group kept here).
Argentina :
Temaiken Bioparc - Red ruffed lemur (small breeding group), black and white ruffed lemur (small breeding group), ring tailed lemur (small breeding group).
Chile:
Buin zoo - Ring tailed lemurs (small breeding group).
Santiago zoo - Ring tailed lemurs (small breeding group).
Guatemala :
La Aurora zoo - Ring tailed lemur (unknown number kept here).
Dominican Republic:
Zoodom - Ring tailed lemur (unknown number held here).