When the Republic of Latvia was proclaimed in 1918, it had no national currency. It was a currency chaos Russian Czarist Rubles and German Ostmarks were all used at the same time. The first Latvian national currency was the Latvian Ruble that was supposed as the provisional currency until peace and economical stability was to be reached. The law establishing Lats as the national currency was approved in 1924.
Already in 1988 first calls of restoring the Lats were made. An art competition was made for new Lats design while official currency was still the Soviet Ruble. On July 31 1990 the Supreme Council of the Republic of Latvia (still not recognized by Moscow) issued law for making the currency system for Latvia.
On 1993 Lats again returned in peoples wallets.
In 2004 Latvia joined the European Union. Latvian government set path to fulfill the Maastricht criteria to join the Eurozone. It was a long road thwarted by economic crisis however on 2012 Latvian government finally voted for joining the Eurozone.
In memory of all-loved former Latvian currency, I've created a T-shirt design named LAT IT BE, referring to The Beatles song Let It Be.