The Cross-National Time-Series Data Archive is a longitudinal national data series and provides ranges of annual data from 1815 for all countries with many associated variables. General categories include demographic data, social, political and economic topics.
See the complete list of variables here: https://www.cntsdata.com/coverage/.

Statista aggregates statistical data on international industries from thousands of sources including market researchers, trade organizations, scientific journals, and government databases. Statista provides access to quantitative data on media, business, finance, politics, and other areas of interest.

iPoll Databank Contains over half a million of U.S. national public opinion surveys in a variety of topics. Includes questions and answers from over 150 survey organizations. Dates of Coverage: last 70+ years

Statistical Abstract of the United States, published since 1878, is the authoritative and comprehensive summary of statistics on the social, political, and economic organization of the United States. Topic areas include population demographics, vital statistics, education, law enforcement, elections, federal/state/local government finances and employment, national security and veterans affairs, social insurance and human services, labor force, poverty and wealth, business enterprise, science and technology, agriculture and natural resources, energy and utilities, construction and housing, manufactures, wholesale and retail trade, transportation, information and communications, banking and finance, arts and recreation, accommodation and food services, foreign commerce and aid, Puerto Rico and the island areas, and international statistics. Dates of Coverage: 1878 (with some data back to 1789)–2012.

Race Relations in American provides records of speeches, reports, surveys, and analyses produced by Fisk University's Race Relations Department from 1943-1970. This information documents the civil rights fight with concentrations on desegregation, migration of African Americans from the rural South to urban centers, the role of the Church in the Civil Rights Movement, race riots and tensions, and the activists of the Civil Rights movement.

Social Explorer is an online research tool designed to provide quick and easy access to current and historical census data and demographic information. The easy-to-use Web interface lets users create maps and reports to better illustrate, analyze, and understand demography and social change. In addition to being a comprehensive data resource, Social Explorer also offers features and tools to meet the needs of both demography experts and novices. To learn more about Social Explorer, visit https://www.socialexplorer.com/product

World Factbook is a publication of the U.S. Central Intelligence Agency that provides information on the history, people, government, economy, geography, communications, transportation, military, and transnational issues for 267 world entities. Dates of Coverage: Varies by country.