stretch of concrete road north from Brink Road in Laytonsville completed in 1923. Another piece of concrete road was built from the macadam road in Laytonsville southeast to Riggs Road at Claysville between 1925 and 1927. The concrete road on the north side of Laytonsville was extended north to near Etchison between 1926 and 1928. Another section of MD 108 was started from MD 29 in Damascus in 1927; the highway from Laytonsville to Damascus via Etchison was completed in 1929. In addition, the concrete road southeast from Laytonsville was extended to Brookeville Road and a new segment was constructed west from MD 97 to Bowie Mill Road in Olney. The final segment of MD 108 between Laytonsville and Olney was started in 1930 and completed by 1933. The highway from Olney to Columbia was proposed as one of the original state highways by the Maryland State Roads Commission in 1909. The portion east of Clarksville was once part of a turnpike called the Ellicott City and Clarksville Turnpike; the portion of the turnpike from Ellicott City through Columbia to Cedar Lane at Elioak was resurfaced with macadam in 1914. Two portions of Clarksville Pike, from Snell's Bridge across the Patuxent River to Highland and a section north of Clarksville, were completed as concrete roads in 1918. The gaps between Highland and Clarksville and at the Middle Patuxent River between Clarksville and Elioak were under construction as concrete roads in 1919 and finished by 1921. Three segments of macadam road were constructed along Clarksville Pike from Olney through Sandy Spring and Ashton to Snell's Bridge between 1916 and 1919. Clarksville Pike was widened with a pair of concrete shoulders from Columbia to Elioak by 1927. The remainder of the highway to Olney was widened to a minimum width of by 1930. MD 108's modern bridge across the Patuxent River was built in 1934, replacing Snell's Bridge. MD 531 was constructed as a macadam road from Waterloo to Jonestown in 1932. MD 175 was relocated, widened, and resurfaced along old MD 531 from Waterloo to Jonestown in 1954. Old Annapolis Road from Columbia to Jonestown was brought into the state highway system as MD 539 in 1956. The new Columbia Pike from Columbia south to White Oak was complete in 1958 but did not become part of US 29 until 1960. Old US 29 from White Oak to Ashton was renumbered