As the Great Depression set in and construction slowed, one more public building completed the district.
The post office had outgrown its space at the Barlow Block again, and needed to move.
As part of the national relief programs, many new post offices were built.
Arthur Ware contributed a restrained Classical Revival one-story brick building at 10 South Highland, between the Cynthard Building and the Presbyterian Church, on the site of what had been the last remaining house on the west side of Main in the district.
It was completed in 1933, the newest contributing property in the district.

The district had been built out, but change continued.
Woolworth's moved into the space at 201–203 Main in 1934.
The government of the Town of Ossining, which surrounds the village on land, moved into Village Hall the next year.

Postwar population growth led to the expansion of two buildings in the late 1950s.
The first was the Presbyterian Church, which received a new Sunday School wing in 1955.
Two years later the high school across the street, serving more students than it was originally designed for since 1937, followed.
Its new wing, completed in 1957, was first used for the junior high school students.
It was built of brick and intended to be architecturally sympathetic.

Most significantly, later in the decade the aqueduct began to carry less water.
New York City had both eliminated one of the two reservoirs in Central Park that it fed, and developed or planned to develop new reservoirs in the Catskills and further up the Croton River watershed, so it needed less water from the Croton aqueduct.
In the early 1950s the city finally stopped using it; some of the communities along the aqueduct kept drawing water from it until 1965.

Automobiles had displaced the railroad as the most common means of transport.
Parkways and other dedicated roads had been built from the city in all directions.
One proposal, made in the late 1920s, called for a Hudson River Expressway to run along the river's eastern shore, paralleling the railroad, from The Bronx to Beacon, including through downtown Ossining.
Governor Nelson Rockefeller, whose ancestral estate Kykuit would have been along the route, introduced a shortened version in 1958, a Tarrytown-Beacon Interstate 487.
After intense local opposition, he canceled the plan in 1971.
The urban renewal funds meant to offset the disruption it would have caused were still available to affected communities.

Like many other established downtowns, Ossining had been adversely affected by the growth of the automobile in the later 20th century.
Local shoppers began taking advantage of improved roads to patronize stores in both enclosed shopping malls and strip malls along major highways like Route 9, outside the village's traditional center.
The village used its urban renewal grants to demolish the old buildings along the south side of Main Street that year in an attempt to revitalize downtown.
Its comprehensive plan drafted but never adopted two years earlier called for mixed-use development projects to replace them.
But they were never funded or undertaken, and the spaces were largely used as parking.
It was the first of many plans that remained largely unrealized, as Ossining went through 15 different mayoral administrations in the remaining years of the 20th century.
During the 1968–74 period, downtown was also the site of several race riots that began at the high school and spilled into the streets.
The community responded by redistricting its schools to ensure racial integration in lower grades.

The 1971 plan had recognized the importance of the buildings on the north side of Main, and historic preservation soon played a larger role in downtown planning.
In 1973, the First Baptist Church became Ossining's first listing on the National Register of Historic Places, and the aqueduct followed the next year.
In 1975, the village followed up with a study of the prospects for rehabilitating and preserving downtown that, for the first time in its planning history, drew on community input.
It recommended resident
As the Great Depression set in and construction slowed, one more public building completed the district. The post office had outgrown its space at the Barlow Block again, and needed to move. As part of the national relief programs, many new post offices were built. Arthur Ware contributed a restrained Classical Revival one-story brick building at 10 South Highland, between the Cynthard Building and the Presbyterian Church, on the site of what had been the last remaining house on the west side of Main in the district. It was completed in 1933, the newest contributing property in the district.
The district had been built out, but change continued. Woolworth's moved into the space at 201–203 Main in 1934. The government of the Town of Ossining, which surrounds the village on land, moved into Village Hall the next year.
Postwar population growth led to the expansion of two buildings in the late 1950s. The first was the Presbyterian Church, which received a new Sunday School wing in 1955. Two years later the high school across the street, serving more students than it was originally designed for since 1937, followed. Its new wing, completed in 1957, was first used for the junior high school students. It was built of brick and intended to be architecturally sympathetic.
Most significantly, later in the decade the aqueduct began to carry less water. New York City had both eliminated one of the two reservoirs in Central Park that it fed, and developed or planned to develop new reservoirs in the Catskills and further up the Croton River watershed, so it needed less water from the Croton aqueduct. In the early 1950s the city finally stopped using it; some of the communities along the aqueduct kept drawing water from it until 1965.
Automobiles had displaced the railroad as the most common means of transport. Parkways and other dedicated roads had been built from the city in all directions. One proposal, made in the late 1920s, called for a Hudson River Expressway to run along the river's eastern shore, paralleling the railroad, from The Bronx to Beacon, including through downtown Ossining. Governor Nelson Rockefeller, whose ancestral estate Kykuit would have been along the route, introduced a shortened version in 1958, a Tarrytown-Beacon Interstate 487. After intense local opposition, he canceled the plan in 1971. The urban renewal funds meant to offset the disruption it would have caused were still available to affected communities.
Like many other established downtowns, Ossining had been adversely affected by the growth of the automobile in the later 20th century. Local shoppers began taking advantage of improved roads to patronize stores in both enclosed shopping malls and strip malls along major highways like Route 9, outside the village's traditional center. The village used its urban renewal grants to demolish the old buildings along the south side of Main Street that year in an attempt to revitalize downtown. Its comprehensive plan drafted but never adopted two years earlier called for mixed-use development projects to replace them. But they were never funded or undertaken, and the spaces were largely used as parking. It was the first of many plans that remained largely unrealized, as Ossining went through 15 different mayoral administrations in the remaining years of the 20th century. During the 1968–74 period, downtown was also the site of several race riots that began at the high school and spilled into the streets. The community responded by redistricting its schools to ensure racial integration in lower grades.
The 1971 plan had recognized the importance of the buildings on the north side of Main, and historic preservation soon played a larger role in downtown planning. In 1973, the First Baptist Church became Ossining's first listing on the National Register of Historic Places, and the aqueduct followed the next year. In 1975, the village followed up with a study of the prospects for rehabilitating and preserving downtown that, for the first time in its planning history, drew on community input. It recommended resident
Downtown Ossining Historic District