Question: At the start of the 20th Century, how many square kilometers was the city that shares a border with the county where William Selden was born?

<P0-S0> throughout the 19th century, philadelphia had a variety of industries and businesses, the largest being textiles. <P0-S1> major corporations in the 19th and early 20th centuries included the baldwin locomotive works, william cramp and sons ship and engine building company, and the pennsylvania railroad. <P0-S2> industry, along with the u.s. centennial, was celebrated in 1876 with the centennial exposition, the first official world's fair in the united states. <P0-S3> immigrants, mostly irish and german, settled in philadelphia and the surrounding districts. <P0-S4> the rise in population of the surrounding districts helped lead to the act of consolidation of 1854, which extended the city limits of philadelphia from the 2 square miles of present-day center city to the roughly 130 square miles of philadelphia county. <SEP> <P1-S0> the great depression was a severe worldwide economic depression that took place mostly during the 1930s, originating in the united states. <P1-S1> the timing of the great depression varied across nations; in most countries it started in 1929 and lasted until 1941. it was the longest, deepest, and most widespread depression of the 20th century. <P1-S2> in the 21st century, the great depression is commonly used as an example of how far the world's economy can decline. <SEP> <P2-S0> Richmond Raceway is in the central portion of Henrico County near Mechanicsville, just north of the Richmond city limits. <P2-S1> The raceway seats approximately 60,000 people and holds two NASCAR doubleheader race weekends per year. <P2-S2> Additionally, Richmond International Airport is located in the eastern portion of Henrico County in Sandston. <P2-S3> Top private employers in the county include Capital One, Bon Secours Richmond Health System, and Anthem. <SEP> <P3-S0> According to the Library of Virginia "William Selden was born 31 January 1791 in Henrico County, Virginia, to Miles Selden (1752-1811) and Elizabeth Armistead Selden (1752-1833). <P3-S1> He was a member for Henrico County in the House of Delegates from 1813 to 1816 and from 1818 to 1821. <P3-S2> He later served as Registrar of the Land Office. <P3-S3> He married first Maria Eliza Swann (d. 1834) 26 November 1833, and they had one child. <P3-S4> He married second Emily Hunter 9 June 1840, and they had eight children. <P3-S5> Selden died 7 April 1874." <SEP> <P4-S0> By the beginning of the 20th century, the city's population had reached 85,050 in 5 square miles (13 km2), making it the most densely populated city in the Southern United States. <P4-S1> In 1900, the Census Bureau reported Richmond's population as 62.1% white and 37.9% black. <P4-S2> Freed slaves and their descendants created a thriving African-American business community, and the city's historic Jackson Ward became known as the "Wall Street of Black America." <P4-S3> In 1903, African-American businesswoman and financier Maggie L. Walker chartered St. Luke Penny Savings Bank, and served as its first president, as well as the first female bank president in the United States. <P4-S4> Today, the bank is called the Consolidated Bank and Trust Company, and it is the oldest surviving African-American bank in the U.S. Other figures from this time included John Mitchell, Jr. <P4-S5> In 1910, the former city of Manchester was consolidated with the city of Richmond, and in 1914, the city annexed Barton Heights, Ginter Park, and Highland Park areas of Henrico County. <P4-S6> In May 1914, Richmond became the headquarters of the Fifth District of the Federal Reserve Bank.