Lawrence city commissioners on Tuesday unanimously approved rezoning a substantial portion of Old West Lawrence from a duplex district to a single-family area.

The change affects properties in 14 full- or half-blocks generally located south of West Sixth Street, west of Illinois Street, north of West Ninth Street and east of Michigan Street.

Existing duplexes will be allowed to remain, but advocates say the change eliminates any incentive for property owners to tear down historic homes to build duplexes.