The houses on Caroline Street and the north, east and south sides of Square 190 were built fairly quickly, an early version of tract housing. And they remained essentially unchanged for decades. The west side of the square and the broader surrounding area were another matter entirely, developing and evolving in a process that took until after 1920 to reach a mature state.

On the one hand, 16th Street and New Hampshire slowly developed as areas for the connected and wealthy. Mansions (Henry White House 1910), some free standing (Henderson Castle, 1888), luxury apartment buildings (Cairo, 1894, Chastleton, 1920, Roosevelt, 1920), churches, a major "Egyptian" temple (Scottish Rite Masonic) (1911 - 1915) and a formal urban park (Meridian Hill Park, 1930) slowly came to fill the available space.[1] The northwest corner of Square 190 was occupied by a high class automobile dealership (1920). Across U the Congressional Club on the east side of New Hampshire Ave opened in 1914.[2]. This area was white, with a few small Black pockets. 15th street was also white with the major landmarks the Portner Flats (1896, 15th east side between U and V) and St Paul's Catholic Church (1883, now St Augustine's) between V and W.

Closer to Caroline, eight-story apartment houses were built at 1915 16th (1922) and 1925 16th (1924). 

On the other hand, to the east a totally different type of development was happening. Washington was very much a southern city, though without a few of the worst features of Jim Crow such as segregation of the street cars. But segregation in DC became much worse during the Wilson administration, as Blacks were barred from any but menial jobs with the Federal government. Blacks were forced to create their own communities with doctors, undertakers, lawyers, entertainment, etc. U Street NW from Howard University to 15th became one such city-within-a-city for the Black community. The Howard Theater at 620 T St NW opened in 1910 as a "Theater for the People" presenting movies and live entertainment for all comers and most particularly the Black community. Duke Ellington performed at the Howard, and lived on the 1800 block of 13th Street from 1910 - 1917. The Lincoln Theater at 1215 U St NW opened in 1922. The True Reformer Building at 1200 U St NW was designed, financed, constructed and used by the Black community. The Whitelaw Hotel at 1839 13th St NW opened in 1919 to provide first-class accommodations for the Black community.[3] There were eventually more than 300 Black-owned businesses in the Greater U Street area.[4]

The development of U Street had an impact on Caroline Street. Whereas the 1920 census counted the street as all white, in 1930 it was over 80% Black. (See census summary.)

Reviewing the Washington City directories shows that from 1924 to 1927 all but six of the houses changed residents. The turmoil of the period is also shown in the vacanies: in 1924 one house (1508) is listed as vacant, in 1925 one (1501), in 1926 six (1501, 1506. 1508, 1510, 1515 and 1517), in 1927 two (1510 and 1518) and in 1928 none.

Among the newcomers were John L Bland (butler by trade, probably born 18 Dec 1897 and deceased January 1966), his wife Martha (probably born 15 January 1890 and deceased October 1970), and children including Norman (born 1 August 1911) and Eloise (born 22 October 1915), who moved into 1501 in 1926 or 1927. According to street tradition, the Blands came as renters but were later remembered favorably by the owner of 1503 and 1501 Caroline, who willed 1501 to John Bland. There was reportedly an uproar about breaking the covenant, but the Blands won and the house remains in the family today.