Famines, pogroms, and steam.
Say, Napoleon conquers most of continental Europe but doesn't go to war with Haiti and doesn't go to war with Russia and Austria. It still is in a cold war with the UK. Latin America still becomes independent in various sized chunks. The UK doesn't try to start the war of 1812 with the US and we continue our economic development without a pause.
France build steamships to compete with the Uk despite the UK's dominance in naval stores. This helps develop railroads which connect the interior of Europe to the ports for the steamship lines. The railroads connect up the coal areas of northern Europe to the citrus and other agricultural areas of southern Europe.
Ireland gets independence because the UK goes broke in the long naval cold war with France, Italy, Spain, Portugal, Germany, and Benelux. This means that they don't put all their efforts into potatos, but develop industry and diversify their agriculture. No potato famine. A smaller population because you don't want to split up your family owned farm, unlike if you are a tenant farmer and your income depends on working children.
France develops rayon earlier in emulation of their sugar beet efforts, so we lose slavery sooner, and less violently. We develop faster without a civil war and freed black people move to the frontier areas like Texas because the white people already own the land in the southeast.
New York stays small without the Eire canal dominating grain transport for a generation. The railroads connect the Ohio and Great Lakes to Baltimore and Philadelphia before they connect to New York and Boston. There is no post civil war agreement on which Pacific coast railroad route to take, the south, the north, or the central, so we don't build a transcontinental railroad until 1885, and the population of the west coast gets more freed blacks and more direct European immigrants by sea.
The ethnic picture of America is very, very, different. Fewer Irish and fewer New Yorkers in general. New England is still Wasp. The southwest is majority black. California is Balkan and Ukrainian and Jewish, with a four way religious split between Catholic, Protestant, Jewish, and Orthodox sects.