According to the head tax description of 1678, Salder was one of the larger villages in the region, with three arable farms, seven half-span farms and 53 dung farms. After the sale of the Salder estate and the transfer of all feudal rights to the hereditary prince August Wilhelm (1662-1731), Salder continued to grow in importance. When August Wilhelm came to power in 1714, Salder Castle became the seat of the princely court and, at the end of the 18th century, also the seat of the Salder office.
August Wilhelm also had a new church built in Salder between 1713 and 1717 according to the plans of architect Johann Kaspar von Völcker, which was to serve as both a parish church and a palace church.
Until Salder was connected to the Braunschweig State Railway network in 1886, the town was dominated by agriculture. In the same year, the Portland cement works were built, whose factories and buildings for workers and managers still characterize the settlement area around Mindener Straße today. Other new buildings such as the district court (1867), the school (1871), the post office (1890) and the dairy (1892) date from the second half of the 19th century.
In the municipal council elections in April 1933, only members of the NSDAP were elected to the municipal council in Salder. This was followed by the standardization of parties and associations and the expulsion of the Jewish families Gutheim and Kleeblatt, who had to sell their property in Salder in 1935. Stolpersteine in Gänsebleek have commemorated the fate of the families since November 2021.
The construction of the Reichswerke Hermann Göring had a major impact on the landscape around Salder: The residential areas of the new town were built in the immediate vicinity in the Lebenstedt district. Brick shell buildings and wooden barracks were erected, road construction began and new railroad tracks were laid in the fields. On April 1, 1942, Salder became part of the newly founded town of Watenstedt-Salzgitter.
Today, Salder is one of Salzgitter's cultural centers, with the municipal museum housed in the castle since 1962. Since 2007 it has been the information center of the "UNESCO - Geopark Harz. Braunschweiger Land. Ostfalen".
The large number of associations based in the district ranges from the VfL Salder sports club, founded in 1892, to the Lerchenfeld allotment garden association, riding club, traditional costume association and volunteer fire department.
