http://www.phmc.state.pa.us/portal/communities/pa-suburbs/post-war/national-trends.html http://www.phmc.state.pa.us/portal/communities/pa-suburbs/po... talks mo

http://www.phmc.state.pa.us/portal/communities/pa-suburbs/post-war/national-trends.html http://www.phmc.state.pa.us/portal/communities/pa-suburbs/po... talks more about it under the heading “Trends in Subdivision Design”. Part of its source material is from a 2002 publication: https://www.nps.gov/subjects/nationalregister/upload/NRB46_Suburbs_part1_508.pdf https://www.nps.gov/subjects/nationalregister/upload/NRB46_S... (8mb PDF, see page 59 of the PDF, with printed page number of 49.)