Bundesautobahn 9

is an autobahn in Germany, connecting Berlin and Munich via Leipzig and Nuremberg. It is the fifth longest autobahn spanning . The northern terminus of the A 9 is at the Potsdam interchange, where it merges into the A 10, also known as the "Berliner Ring", about away from the Berlin city limits. The shortest route from there into Berlin would be the A 10 (east) and the A 115 (AVUS). The southern end is in the Munich borough of Schwabing. On its way, the A 9 passes through the German states of Brandenburg, Saxony-Anhalt, Thuringia, and Bavaria. West of Leipzig, the border between Saxony-Anhalt and Saxony crisscrosses along the autobahn. In Bavaria, long sections of the Nuremberg–Munich high-speed railway run parallel to the autobahn. Plans for a European motorway connection from Berlin to Rome were already developed from 1927 by a private MüLeiBerl (Munich-Leipzig-Berlin) company. However, construction of the A 9 was not begun until the 1930s as part of the Reichsautobahn project set up by Nazi Germany. It was inaugurated in sections, beginning in 1936 with the Strecke 16 between what is today's Schkeuditz interchange (present-day A 9 and A 14) near Leipzig and Bad Berneck im Fichtelgebirge, in length. With the opening of the second lane near Schnaittach in 1941, the last gap was closed. This makes the A 9 Germany's first completed autobahn. After World War II, the section from the inner German border to Berlin served as one of four transit access roads through East Germany (GDR) toward West Berlin during the Cold War era. The road was closed by the Soviet Military Administration during the Berlin Blockade. The U.S. Army Europe under Lucius D. Clay considered a tank offensive to forcibly reopen the route, but chose not to implement the plan since it had no guaranteed chance of success and would lead to World War III if the Group of Soviet Forces in Germany chose to resist. The route was finally reopened after the success of the Berlin Airlift. Yellow signs with "TRANSIT" in black letters marked the allowed route.